Alex (A Merry Little Christmas)
From Tardis Wiki, the free Doctor Who reference
Alex was a relative of Heather McCrimmon.
He celebrated Christmas at Granny McCrimmon's house along with Heather and the Tenth Doctor. During the celebration he stood next to Heather and her dad. (COMIC: A Merry Little Christmas)
Behind the scenes
It wasn't mentioned in the comic what kind of family relation Alex had to Heather.
