Using a throw away for this. Also on mobile so its going to be poorly written.
This started last year on Christmas/ boxing day. 3 major characters: myself, my sister in law ( I'll call her SIL), and my cousin who is married to SIL. Now our families are extremely close, so close that I consider cousin as a brother. I can go to his house unannounced, eat dinner, sleep over, then leave in the morning no problem. I'm 20, SIL is 31, and cousin is 34.