Decided to make this my official ref-layout for my AU designs (heres raph plus some more info) so here’s Leo - the eldest son and the leader of the group

Info about the Blue boi under the cut

Hamato Leonardo, also known as Leo (or Nardo, blue guy, Hero boy and Fun-police) is the eldest son of Splinter and the most traditional of his brothers, taking both his training and the prophecy very seriously, studying his families history in detail to please his father and ancestors, to become the ultimate warrior. Due to being the eldest and resembling Splinters younger self, Leo is the golden child and despite him denying it, it’s very clear that Splinter favorites Leo, often training with him, teaching moves and wisdom he would never show his other sons. Due to this, Leo has developed quite the denial and perfectionist complex, in his eyes he always has to be good at everything no matter what while both Splinter and his ancestors teachings/the prophecy can never do anything wrong and should always be followed no matter how wrong they sound - even if it means to hurt those close. 

As the eldest, Leo is also destined to become the deity of the body, gaining powers that strengthen his body and give him abilities like super strength or lightning speed which he has a hard time controlling at first, which frustrates him a lot. While he is very skilled with his swords, the bow and arguably the best fighter on the team when it comes to weaponry, Leo isnt as coordinated when it comes to fighting with only his fists which is a bit unfortunate considering his powers.

Being Leader, Leo is the calm and responsible one, taking missions very seriously and always prepared with a plan though he can get really irritated when his brothers dont immidiatly follow his lead, question his plans (especially Raph whom he gets into fights a lot) and goof around as he really never allows himself to be a kid. However, he is very much a nerd, specifically he’s really into old, awful cartoons and anime even writing self-insert fanfiction about him and his cartoon heroes, whom he tries to imitate a lot, going on adventures (and dates) among other things. Literature was always one of his interests, spending hours reading not only comics but thick books, mostly about space, autobiographies or japanese myths/legends while also occasionally writing poems he comes up with when he meditates. Just like Donnie, Leo is fluent in japanese and watches a lot of his shows in its original language while getting writing lessons from Splinter. Leo’s music taste is also very much influenced by his father, listening to japanese folk songs - though he does have a soft spot for j-pop and Vocaloid.

A few other fun facts about the boy in blue:

He only wears the scarf because the texture of it makes him very comfortable and also because it makes a good cape

Very sensitive tongue, any food texure his tongue doesnt like makes him immidiatly gag

Stims by flapping his hands and sometimes does a happy little jig when he gets excited - he is however very embarressed by it, even telling his brothers to stop doing their own thing (like Raph tapping his feet/ drumming)

Can absolutly not interact with people he’s crushing on, like his brain will enter gay-panic-mode and shut down, thats why he prefers to crush on cartoon characters instead

Really tries to avoid April because she’s nothing but trouble, however she is the first person Leo will go to when he has a problem/secret he cant tell Splinter about

Leo’s favorite brother is Donnie, they often hang out and talk about literature and plans while listening to hyperpop Vocaloid songs, Mickey is his second favorite and while they dont activly hang out together they do occasionally talk about cartoons and Leo does appreciate the hug attacks his younger borther is known to do, Raph and Leo often fight due to their different views on the prophecy, Raph’s overall attidute and disrespect towards his leadership and the family tradition - though when they do get a long its mostly over movies and which fictional character is cooler

Also, once Karai gets recruited into the family, Leo and her hang out constantly, training together and confide in each other - she would definitly help him be less serious and probably give him some dating advice from one gay to the other while talking about the latest shows and whatever horrible anime Karai found on the internet that they will definitly not be obsessed with for at least a week.