. Scout .
RED . Is incredibly sensitive about his teeth. He is ever so slightly 'buck toothed', but he doesn't get it from his mother, who has perfect teeth... He gets it from the father he doesn't know. If anyone makes a jab at his appearance, he becomes violently offensive incredibly quickly, as they're all he has left of his ambiguous father.
BLU . Being the youngest of all his 8 siblings, he was the centre of his mother's attention the majority of the time. As a result, he was often picked on by his older brothers. This makes him incredibly jumpy and skittish, as he was constantly on guard back home in Boston.
. Soldier .
RED . Has a soft spot for just about everything adorable. He hides it, as he wants to be seen as the one member of the team that routinely fits in with the "American Soldier" stereotype - that being 'tough' and 'manly', though in reality he's a good deal softer. Take him to a farm with baby animals, and he'll almost certainly end up turning red and muttering incoherent strings of babble, trying to hide his joy. Also gets flustered incredibly easily, something that the BLU Demoman loved poking fun at, when they were close.
BLU . Reads comics in his free time. He's not too bright, so the only books he reads are based on/centred around war (non-fiction), and the various works of Sun Tzu. Aside from that, he loves nothing more than curling up after a long day's work, with Lt Bites in his lap, reading superhero comics. He prefers Marvel, Captain America being his all time favourite hero. He has a pair of reading glasses, but they won't fit under his helmet, so he never wears them.
. Pyro .
RED . Is an excellent cook. Nobody knows why, or how he picked up the skills he has, but no-one on the team is able to deny that Pyro is a bloody good chef. I imagine that the cooking duty is on a rota, and that Pyro is the most frequent chef, followed by Spy, then Heavy and occasionally Medic. Demoman is not allowed within 10 feet of the kitchen at all times.
BLU . Suffers from Ornithophobia, and as such, flatly refuses to go near team mates carrying birds on their shoulders. Pyro will only venture into Medic's lab after a firm confirmation that all the doves have been removed from the area. Some think it's an issue that stems from his childhood, others think he's just batshit insane.
. Demoman .
RED . Before the loss of his left eye, suffered from Anisocoria. well that was short and sweet, jesus.
BLU . After trying to convince a therapist that his adoptive mother and father were brutally killed by the Loch Ness monster, the Demoman was diagnosed with a minor form of Schizophrenia, and was put on a course of medication for a controlled period. However, after documenting the Demo's mental state in compliance with the medicine and noticing no change, his therapist revoked the prescription, merely syphoning him off as 'a little daft'.
. Heavy .
RED . Heavy is incredibly jealous of Scout's speed and agility, though he'd never admit it.
BLU . Used to have a small pet, back in Russia. Heavy was a large child, and was often picked on, or avoided because of his strength. One winter, he found and befriended a tiny robin, but she died in the following winter, when food was scarce and the cold unbearable. It hit Heavy hard, and for the longest time he was incredibly sad. The bird's name was Sasha.
. Engineer .
RED . Is an Objektophilie. Not in a sexual way, but I believe he has genuine attraction toward the Sentries and Dispensers he builds in the battlefield, hence the emotional response when one is sapped or destroyed by a BLU.
BLU . Is the only married man among the Mercs. He has a small child, a little girl, who's just 6 years old, and carries a picture of her and his sweet wife in a locket - which can be found tucked away in the bottom of his toolbox.
. Medic .
(there are 3 because I answered them in a different post - not intending to have to do all the Mercs c': this also means they're not separated into RED and BLU, so I'd probably assign 2 to both teams, 1 to BLU, and 3 to RED.)
1 . He doesn't actually need the glasses he wears. They have no prescription, which is why he flatly refuses anyone who asks to try them on. He wears them to mimic one of his greater idols/influences, Sigmund Freud, the "founding father of psychology".
2 . Is the only member of the team who is gay. I can envision the others being Straight, Bisexual, or really not giving a damn about what goes where, but the Medic is the only one I can see being purely gay, and being interested in only men. I don't suppose being stationed around 8 other cuties is much help, either~~
3 . Adores the sensation of flesh on flesh - and not just 'skin'. Medic often removes his gloves mid-operation, and sometimes even leaves them off entirely, purely because he revels in the sensation of his hands being plunged into another man's gut.
. Sniper .
RED . Is secretly a lover of deep-fried food. When the Scout originally introduced him to America's trademark Fast Food restaurants and take-outs, he was repulsed and tried to get out of actually eating any. When he finally keeled over and tried some, the reaction was similar to Squidward trying a Krabby Patty. There is no other metaphor that would convey it quite so clearly.
BLU . Has a scar on his left ankle, which he earned in the Australian Outback when falling from his perch in a tree.
. Spy .
RED . Suffers from depression and social anxiety, and is one a course of medication because of it. Refuses to admit this to Scout's mother, who he knows will only fret needlessly.
BLU . Is bisexual, and actually did fall in love with the RED Spy, for a long period of time. Also lacks the experience of the RED Spy, and often "goofs up", or makes rookie mistakes that cost the team their victory. However, he is a very good liar, which makes it easy for him to cypher the blame onto someone else.