some Leo headcanons I have
Leo doesn't know what day his birthday is. He knows its in July, but he hasn't done anything on it since he was 8 and he used to act like it was/wasn't on certain days based on how well they went (he thinks its the 7th, but he hates the number 7 so he ignores it).
Leo has stolen and crashed a police car. He will do it again.
Leo's mother and Aunt Rosa both had dreams from Gaea that told them Leo was going to kill Esperanza, but Esperanza took it as an "he'll do it on accident bc he doesn't know how to control his powers" and Rosa took it as "It's a sign from God and this child was sent by the devil".
He's asexual biromantic, but in love with the idea of being in love.
He learns a form of script-based magic - the same thing that is etched on each stone used for the Hecate cabin. Jo is his teacher, but when he visits camp all of the Hecate cabin are happy to help him too. He views it as a code instead of magic, and only ever uses it in the things he builds because he forgets it can be useful on its own.
He's a Fall out Boy stan. Loves all types of rock too, but FOB was his gateway into it.
Every time he went to a new school if they had a music program he could join for free he would. Originally he'd just choose a new instrument every school, but on his third try he learnt drums and decided to stick with it.
HIs eyes look like yooperlite while it's glowing, but more like burning coals while he's using his powers.
On that note, Leo's body temperature can be way hotter than the normal person's. On a normal day where he's fine in everyway, he's hot but not hot enough for people to think he's feverish. When he's excited his temperature rapidly increases, as it does with stress. When he forgoes sleeping his body forgets to regulate his temperature, which leads to him either going very cold or very hot.
He can't really get fevers at all really. It's also very hard for a lot of illnesses to effect him because half the time he burns it up before he even knows its there. When he does get sick it's really bad though, because his immune system is actually pretty weak.
Related to that, he is the only known person who can currently be a theoretical host to a thermophile virus. Not that he would, but it is a thought that has crossed his mind.
He has a hobby of making little robots. He makes Piper a bronze eagle one as a present and he slowly starts to make them for his friends
Annabeth gets a cat because he thinks she has cat vibes and an owl would be basic. Percy gets an otter because Leo did not want to think about making a robot fish that works well out of water. Frank gets a chameleon as a joke, but he makes it so it can turn into a small dragon too. Hazel gets a snake, again for the vibes. Nico gets a lizard. Just like, a nondescript lizard. He makes Reyna a bronze dog to "complete the metal set", but it's based of a Molossus of Epirus instead of a hound. Jo and Emmie get matching gryphons, and Georgina's little robot is a llama. Leo makes himself a wolf in honour of Jason.
On the topic of making things, Leo also gets really into all forms of metalsmithing. Which includes making jewellery, which leads to him getting a lot of piercings. Piper does too, because they went to go get the piercings together. He loves giving people little friendship bracelets, and charms, and ornaments. He makes people themed cutlery sets.
His love language is gift giving, if it's not obvious.
He stays in contact with Apollo, but in order to not upset Zeus they frame it as 'music lessons'. As the inventor of the Valdezinator (and its best player), it's a pretty good excused. Leo does make new instruments occasionally when they feel like they're pushing the 'lesson' excuse.
They fr just gossip during them though, and then give each other a scuffed form of therapy. They go from talks about petty drama to unanswerable philosophical discussions to jokes that make no sense.