It's difficult to find a thread in Queen's music cause most of the time the subject matter is so abstract and the enormous changes in the style of music they played are quite distracting.  But if you look, there are themes and it's really fruitful when you find them. Themes, even when they are unanalysed are how fans can identify with 99% accuracy a "Roger" song, if not by the music, by the lyrics...  Regardless I never really took the lyrics into account because I thought the music mattered above all else.

First, I'd like to paint the picture of a young Freddie for those who aren't super familiar.  He was born in Zanzibar in 1946 to Jer and Bomi Bulsara.  If any of you have seen his birth certificate, it's quite humourous because there are mistakes and cross-outs everywhere (talk about identity crisis!).  When he was about eight he was sent to boarding school in India.  It's hard to speculate what this must have been like because he was very secretive about his past.  By watching way too many documentaries and reading too many biographies, I think this would've been a hard time in his life.  This may be attributed to being thousands of miles from his family, political and social unrest in his home country, upholding his faith as well as his struggle with his sexuality amongst other things.  The family moved to the UK in 1964 due to these difficulties in Tanzania.  As his sister, Kashmira once said in an interview, she and Freddie were afraid of being marked as "different" from the cultural stereotype.  This is all before Queen began...

So where's your proof?
Mother mercury mercury
Look what they've done to me
I cannot run I cannot hide
                                            (My Fairy King from Queen I)
Apparently during the Queen I recordings, after writing this line, Freddie said to Brian that he was going to become Mercury, because his mother was the mother Mercury in the song.  Hmm, something to think about.

Mama I'm gonna try behave
Mama I'm gonna be your slave
I'm gonna serve you till your dying day
I'm gonna keep you till your dying day
I'm gonna kneel down by your side and pray

Liar liar they never ever let you win
Liar liar everything you do is sin
Liar nobody believes you
Liar they bring you down before you begin
Now let me tell you this
Now you know you could be dead before they let you (be)

                                                         (Liar from Queen I)
Liar has a very angry and upsetting, almost tortured air about it.  I'm fairly sure Richard Blackshaw had a go analysing this a while ago, but I can't remember what he said.  It's been widely acknowledged that Liar is a type of "confessional" song.  A church organ features in the instrumentation and the first two lines indicate that Freddie's in some kind of confessional booth, professing his sins. This is bizarre on certain levels, because of the Catholic imagery associated with confession, while Freddie theoretically follows an entirely different faith.  For this reason the first lines of this song could easily be a play on words, as Freddie could be confessing to his real father.  This is a likely interpretation because Freddie also mentions his mother.  The lines are pretty self evident, I'm sure you can draw your own conclusions.

It's so funny there's nothing to laugh about
My money that's all you want to talk about
I can see what you want me to be

No beginning there's no ending
There's no meaning in my pretending
Believe me life goes on and on and on
Forgive me when I ask you where do I belong
You say I (you can do it) can't (you can do it
You can go and) set you free from me
But that's not true

                                 (In the Lap of the Gods - Revisited from Sheer Heart Attack)
While Freddie went onto a bit of a tangent in his songs, writing primarily about Greek mythology (Queen II) and historical figures and tramps in Sheer Heart Attack, Freddie only indirectly touched on this issue with his parents in The Lap of the Gods Revisited.  While it's generally considered that In the Lap of the Gods is about his then girlfriend, Mary Austin, it's hard to know what Revisited is about because the terms are so general.   To me, in the first verse Freddie's trying to convince his parents that his lucrative career as a musician is going to work out.  At this time, Queen were having problems with their record company Trident since they hadn't made much, if any money from their two successful albums and tours.  So you'd imagine while Freddie, himself, was doubting his career prospects in this band, he felt he needed support and maybe all he was getting was criticism.  The repetitious line "I can see what you want me to be" is very prophetic in these circumstances because Freddie acknowledges that he's deviated from his parents' image of the prodigal son whilst pursuing his dreams.

The second verse, meanwhile, identifies his general "neverending" frustration and his feelings of disconnection from the family unit.  The line (fragmented by the "you can do it"s) is kind of sad, "You say I can't set you free from me, but that's not true".  It's like he's determined to be completely cut off from their criticism while also cutting himself off from other things.

But I'm just a poor boy and nobody loves me
He's just a poor boy from a poor family

Mama mia, mama mia, mama mia let me go
                                             (Bohemian Rhapsody from A Night at the Opera)
Admittedly, after doing a Bohemian Rhapsody analysis (& receiving many a bitchy email about it), I really don't know what the song is about.  It's difficult to know especially considering Freddie always said that he never put much thought into it.  In the context of this analysis, I think it's Freddie imagining he really had to answer for his mother, repenting for murdering another man (I think it's called an analogy or something).  Notice it's got the same sense of tragedy as Liar did -- and in Liar  Freddie was only apologising for his slightly debacherous lifestyle.  But you have to notice that he doesn't necessarily repent because he killed the guy, he's repenting cause he disappointed his mother.  The second part in the song (the I see a little silhouetto of a man bit), I most definitely think it's the character's journey into hell and still feeling accountable in death as he did in life.  I think this was a big fear of Freddie's, since he explored other faiths aside from Zoroastrianism and perhaps going to hell was a possible consequence.... remember this is only speculative!!

Another line I came across, quite by accident is one from the Prophet Song.  I don't think this is really proper evidence since it was written by Brian and it's a complete rehash of what was written in Chapters V- X in Genesis:

From mother's love is the son estranged
Married his own his precious gain
                                             (The Prophet Song from A Night at the Opera)
This could be interpreted as the the son is estranged because he married his "own".  Pretty irrelevent, anyway!

Faiths Freddie explored include the already mentioned Greek mythology and Catholism, existentialism (in Bohemian Rhapsody), Islam (in Mustapha), Christianity (in All Gods People) and issues about morality and basic philosophy in songs like Don't Try Suicide and Keep Passing the Open Windows.  Certainly stuff to think about ; )

Guilt stains on my pillow
Blood on my terraces
Torsos in my closet
Shadows from my past
Life is real life is real
Life is real so real

Loneliness is my hiding place
Breast feeding myself
What more can I say?
                                            (Life is Real (Song for Lennon) from Hot Space)
Like Bohemian Rhapsody, there's this violent imagery combined with a guilty sentiment.  Despite the musical style was a lot like Lennon's, the lyrics were a lot like Mercury's probably because Lennon's music reminded him of difficulties in his earlier years.  Although I had never understood that "breastfeeding myself" line, it really makes sense that he was trying to compensate for the relationship he had with his mother even at 35 years old.  What more can I say?  The following years, Freddie wrote about other topics, such as the difficulties in love and life (consider the entire Works album) as well as becoming involved in the Highlander-esque A Kind of Magic.  It's really interesting that nearly ten years later on the Innuendo album, Freddie would sing about facing challenges completely independent of any support.