Authors with experience, I need some help

[Kai's]

So, I'm a young 14 yr old girl and I'm writing a dual pov about two girls who aren't related but are still 'sisters at heart' and the story is mainly revolved around Elena, whose 19, and her trainer Ivy, that's a little younger than Elena by a few months.
So my question is, how can I write the characters to be likeable and for the reader to get attached to them?

[✰ Brynlee ✰]

i’d give them character traits that are relatable and/or admirable for people who are around the same ages as them that might be reading it, that’s one of the big things that makes me love certain characters so much!

[TKZ]

Is there specific plot to the story?
Is it meant to be serious or can you add goofy quirks about them. Like one needs a morning Starbucks or is always has a specific candy, etc.

[Kai's]

@Brynlee - I will do, but I need to ask what kind of relatable because it's a fantasy, fiction book? (sorry if I'm being a bother)

[Kai's]

@TKZ - Well, she (Ivy) can be goofy and fun but she's also serious when needed. Definitely not a startbucks coffee or candy😂💅🏼this is a fantasy, fiction book with magic