In the first season of Forever Knight, Natalie lived in a smaller, differently furnished apartment from the one she now has.   Sometime between the first and second seasons, she moved.   And, although her new apartment did not appear in any of the episodes of Season III, it continues to be her home.
        She lives on the second floor of an older apartment building, one with large picture windows, white-painted panelled doors onto the common hallways, and glass-panelled doors between separate living and dining rooms.   There are clearly two entrances to the building, since Natalie has approached her apartment coming from either direction.   In one case, she had a lot of shopping; so it's fair to assume that, on that occasion, she was coming from the elevator.   From that direction, her apartment (No. 218) is the first one along on the right.   From the other direction, you probably are coming from an emergency stairwell on the other side of the building, probably leading down to the parking lot.
        Although it is a common hallway, it is decorated with pictures and vases of (probably artificial) flowers.

The outer door of the apartment opens into a lobby, which Natalie has furnished with a demi-lune table on which is a lamp, and a vase or maybe candlestick (which she used to hit the vampire Spark in "A More Permanent Hell", so that she could get away from him).
        Off the lobby is a corridor, which runs between the living room on the right, and a smaller room on the left, which presumably is the bathroom.   Natalie has hung the walls with pictures, and put a tall narrow display cabinet against the wall common with the living room, just beyond a mirror.   There is a picture also at the end of the hall, hanging over a table with a vase of flowers on it.   There is then a slight dogleg to the bedroom door, which presumably faces the door to what must be the bathroom.
        There is another door, immediately off the lobby just after you pass the hall table.   Only the slightest glimpse was ever filmed.   Us­u­al­ly, it is off scene be­hind the camera, or hidden by the doorframe when the lobby is shot from inside the living room.   Presumably this door goes into the kitchen.   In "Be My Valentine", Natalie came into the living room from this di­rect­ion, telling Nick that she had just put on her "two-minute gourmet" dinner.
        The direct route through the lobby, straight ahead as you come in, takes you through an open doorway into the living room.

Natalie's living room

The door into the living room from the lobby is in the left corner of the rear wall of the living room.   To its right, Natalie has a pair of small pictures hanging on the wall above a shallow glass-topped table, which matches the coffee table in the centre of the room.   It's hard to make out what is on this table; but I'm assuming that, whether or not this was true when she first moved in, she now has a telephone/answering machine there.
        To the right, she seems originally to have placed a little table to hold a lamp; but she must have later decided instead to put the lamp on the glass-topped table, which is where it remains in the fourth season.

        The side wall (common with the bedroom) has a fireplace in the centre, with tall bookcases on either side.   At the time of the second season, neither was really full.   Yet having so many bookcases - there's another in the bedroom - suggests that Natalie is quite a reader.   As those who read a lot know all too well, bookcases fill up alarmingly quickly.   But, of course, at that time Natalie had only recently moved in.   Presumably, she'd had less shelf space in her old place.
        Assorted knick-knacks are on the mantelpiece over the fireplace; and a large picture hangs over it.   In "Curiouser and Curiouser", this was replaced by a picture of a girl in a boat - one of the many Alice references in that episode, for, of course, Lewis Carroll was inspired to write Alice's Adventures in Wonderland by a story he told to Alice Liddell and her sisters during a day's outing on the river.
        The far end of the living room is taken up by a large picture window, veiled with light net curtains concealing Venetian blinds, with heavier drapes tied back on either side.  It was through this window that LaCroix saw Nick and Natalie kissing in "Be My Valentine".
        The centre of the room is occupied by a white loveseat set facing a matching armchair, both piled with fancy fat cushions.   They are set at right angles to the fireplace, with a coffee table between them.   In addition, the loveseat has set by it at the fireplace end a small table only large enough to hold a drink or an ashtray.   This seems likely to be Natalie's usual seat, since it is the place she automatically went to sit down in "Be My Valentine".   Oddly, though, the reading lamp is set on a table at the opposite end of the loveseat, with a stand­ard lamp be­hind the armchair op­pos­ite.   This is some­what of a problem, since people tend to have a favourite place to sit; and, as all readers know, it is essential to have good light directly on your book.   It is also useful to have somewhere to park your book when you get up - and a place to stack several texts and a notepad and pen, if, as seems likely, Natalie sometimes does research at home.
        I am therefore making a slight change to the decor.   Since Natalie had only recently moved into this apartment at the time we saw it in Season II, it is not unreasonable to assume that she set such furniture as she had around the room, but might later have switched things around and augmented them with new purchases.   So I am assuming that she has moved the little drinks table to the armchair, where guests usually sit, replacing it with the larger end table and its lamp.   This affords her ample space to set down something she is reading, be it work or light entertainment, have a place for a snack or coffee, and good light to read by.  But it also makes a little more space on the far side of the room.
        The remaining wall of the living room, opposite the fireplace, is dominated by the glass-paned doors to the dining room.   Nevertheless, there is enough room for Natalie to have hung a picture on the side near the window.   And here I have taken the liberty of making another change, adding a small writing desk under this picture.   This is a dainty antique lady's desk, with a flap that comes down to make a writing surface, and pigeonholes inside.   It's a wholly impractical piece of furniture in a modern house, for it could barely take the weight of a laptop.   Natalie doesn't actually use it for anything much; it's more of a decorative accessory.   She hasn't even bothered to put a chair with it.
        Against the wall on the other side, between the doors to the dining room and the door to the lobby, she has put a tall narrow display cabinet and another picture.

Natalie's dining room and kitchen

Little of the dining room and nothing of the kitchen ever appeared on screen.   Nevertheless, much may be deduced.
        The dining room is accessed through the doors from the living room; but the kitchen seems to be accessed through a door off the lobby.   Obviously, there must be a door between them - a door rather than a hatch, given the older style of the apartment building.   Given that the kitchen is roughly parallel to the lobby, it must be a fairly small room - a mere "efficiency" kitchen, with counters, cupboards, and appliances, but no seating.
        Since the bedroom and living room both have large picture windows, it is likely that the dining room has also, with the same net curtains and heavy drapes as in the other rooms.   This means that the end wall of the dining room is mostly window.   Furthermore, a good part of the wall common with the living room is taken up by the glass-paned doors.  This gives a good view of the living room; but usable wall space in the dining room is significantly reduced.
        Natalie's dining room furniture is very traditional in style - or, at least, that is true of the one chair we see.   But, given the rest of the apartment, this suggests that she has a full suite, with a sideboard and china cabinet.   These presumably are set against the remaining walls of the room (one of which is common with the kitchen), though these were never filmed.   Around and between these pieces of furniture, there likely are pictures hung on the walls, for Natalie certainly seems to have pictures everywhere.
        Although furnished for formal entertaining, the dining room is actually used by Natalie as an auxiliary office.   Her PC is set up on the table, with plenty of room to spread out papers.   Of course, a full sized dining room would still afford her space to eat at the table, though she may have fallen into the habit of eating her "two-minute gourmet" microwave meals on her lap in the living room.

Natalie's bedroom

Natalie's bedroom is at the end of the hallway off the lobby. It's a corner room, with a a larger window on the end wall, matching in size and design the window in the living room, and a smaller window opposite the door, presumably on the side wall of the apartment building.
        When you enter the bedroom, most of the wall on the left is taken up by a clothes closet with white louvered doors.   Nick threw Spark through these doors in "A More Permanent Hell"; but presumably they've since been replaced.
        Natalie has a double bed, with a plain polished wood bedhead.   She favours plump white pillows and duvet - which, when one comes to think of it, matches her taste in loveseats.   The bedhead is set against the outer side wall, with a picture hung over it.
        There is a pair of bedside tables, matching the bed in style.   Each of them has a small lamp set on it; and Natalie seems to like to leave these lights on when she goes out at night, since, in "A More Permanent Hell", they were already on when she fled to the bedroom to escape Spark.   The one on the left is under the small side window in the room.   Natalie keeps a vase and a couple of framed photographs on it.   The bedside table on the right has another vase and a candlestick.
        Beside the bed, Natalie has a rug.
        The end of the room is largely taken up by the same sort of picture window found in the living room, with net curtains and heavy drapes.   Beside it is a tall white bookcase (into which Spark tossed Nick when they were fighting over Natalie).   Again, it is reasonable to assume that it has since been mended.   There seems to be something near it: perhaps an armchair, with a table lamp.
        The remaining wall, which is common with the living room, never appeared on screen.  However, given the furniture we do see, it seems likely that Natalie has one or more chests of drawers along this wall, almost certainly matching the bed and bedside tables - polished mid brown wood in a plain style.

There is one problem with Natalie's lovely apartment.   In the first season, she had a rather smaller place - no separate lobby or dining room, and no big picture window.   And she had different furniture.
        So how can someone who must only be a few years out of medical school afford so much so fast at a time when one would expect that she would still be paying off hefty student loans?   Of course, she does not have a large mortgage and several children to support.   But a public employee such as a junior forensic pathologist will not be paid anything like as well as a specialist in private practice.
        It is possible, of course, that Natalie has managed to pay off her loans, perhaps with help from her family.   And all her lovely furniture may be maxing out her credit card payments, having been bought on time.   Or, alternatively, given the conservative style, perhaps some of it is inherited.
        At any rate, there is no doubt that - however and whyever it happened - there was a significant change in Natalie's housing between the first and second seasons of the show.