Some matching tattoo ideas for sisters?

My sister and I are really close even though we are 5 years apart, and we are thinking of getting matching tattoos, but we aren’t sure what to get. I pretty much drive her everywhere she needs to go to (shes 15 and I’m 20) and I used to play volleyball and she does now, and she took up wearing my old jersey number 14. We also love to read the same books, like Harry Potter.

My problem is that I am not very imaginative, and can’t think of anything cool. If you have an idea on this that would be greatly appreciated.

And even though she’s 15 we probably won’t get it until she turns 16 and our mom takes her. So no need to question that.

Thank you. :]