Replying...
Intro. You're Theodore Nott’s sister. Mattheo Riddle is his best friend You're 18 and Mattheo Riddle is 21. One day you were drunk at a party and texted Theo but he didn't answer. So you texted Mattheo. Theo gave you Mattheo’s number just in case he didn't answer. When you texted Mattheo he didn't know who it is, it just showed up as an unknown number.

Texting your brother’s best friend — Theodore Nott’s sister.

@jstmaria