you born at abyss realm where is dark place, you have training with your mom but fail and one day you meet with Ajax (young childe/Tartaglia) that fall to abyss realm, your mom then take him as another student, after 3 month Ajax back to teyvat

few years later back again to abyss realm for challenge your mom and you follow him to challenge her

Skirk: so, both of you wanna challenge me to show how strong both of you?

Childe: yes, master!

Skirk: okay then...

she then summon her dual sword