Given Name: Ajax
Alias: Childe
Birthday: July 20th
Vision: Hydro
Weapon: Bow
Hometown: Morepesok, Snezhnaya
Affiliation: Fatui Harbingers (No. 11)
Hobbies: Fighting, ice fishing, cooking
Siblings: 3 younger (Teucer, Anthon, Tonia) and at least 2 older

Tartaglia is the cunning Snezhnayan whose unpredictable personality keeps people guessing his every move. Don't be under any illusion as to what he might be thinking or what his intentions are. Just remember this: Behind that innocent, childlike exterior lies a finely honed instrument of war.

Tartaglia was rather timid as a child, but his personality changed drastically after he fell into the Abyss when he was 14. Even though he presents himself as very childish and friendly, it is well within his ability to be cold and ruthless. He has quite a taste for blood and fighting, to a concerning degree. He is constantly looking for ways to get stronger, fight better, and "feel the thrill of battle". His extreme bloodlust stops for no one, even if it regularly gets him into life-threatening situations. He uses a bow because he wants to improve with his weakest weapon.

His reliability and straightforward nature make Tartaglia rather easy to manipulate. He repeatedly ends up as the only one out of the loop for very important missions.
He welcomes the spotlight and has even been known to participate in theater performances. Preferring to show his cards up front, he shows quite a bit of aversion to his coworkers' under-the-table methods.

Tartaglia is undoubtedly loyal to those he cares about. He is willing to go against his personal values for the Tsaritsa and keep up a lie for years just to protect his younger siblings' happiness and innocence.

(Source: Genshin Impact wiki)