It's interesting that both Éowyn and Faramir are the younger of two siblings. There's a ton of psychology on birth order out there, and most of it's too generalized to apply to FICTIONAL characters, but it's still interesting stuff.
In doing a bit of reading, here are a few things I've found:
- Second borns understand their older siblings really well, but usually the opposite isn't true.
- Second borns are peacemakers, and they're very sensitive to anger.
- Second borns have a sense of justice based on necessity.
- I like this theory I found in a psychology textbook: "When second borns go for a walk in the woods, they watch the ground around their feet to avoid obstacles, but they sometimes end up going in circles."
- A Second born's strategy for survival: perfectionism and logic.
- What's achin' them: a sense of inadequacy (note here: first borns usually suffer a sense of guilt).
- Their biggest challenge: being outdone by their older sibling.
- I also like this: "If the first and second born were both farmers, the first born would farm as much land as possible to impress others, but the second born would farm modestly to keep things manageable."
- And: "Behind the wheel, first borns would drive cautiously as if other drivers were out to get them, while second borns would drive angrily as if everyone were violating the rules."
- Second borns tend to listen for mistakes when other people talk, while first borns listen only to other people and not themselves.
It's really easy to imagine a lot of these birth order tendencies existing between the two sets of siblings in LotR, even though there isn't much natural interaction between the characters themselves (we never see Boromir and Faramir together, and Éomer and Éowyn are always caught up in the middle of some royal crisis).
Of course, no psychological "tendency" applies to every case, and certainly that's true in LotR. Take Éowyn, for example. Her parents died when she was still a child, and the man who adopted her and her brother Éomer already had a son of his own. So it might be that Éowyn acts more like the Last Born of three children.
Some characteristics of third-born children:
- Their strategies for survival are based on seeking emotional strength and attacking their oppressors.
- "When and if third borns go for a walk in the woods, it's only to help others find their way through."
- While second borns listen for mistakes in what others say, third borns are always trying to determine others' motives.
- They're intent on helping people, believing that the unjust world is full of victims, but also because they strive to please.
- Their source of anger? Being put down.
- What they missed in childhood: protection.
This sounds more like Éowyn in my opinion. First born children are motivated to achieve (Boromir, Théodred). Second born children are great managers (Éomer, Faramir). And third born children are the ones who take the risks and question authority (Éowyn).