Thomas has known that he's Harry's brother longer than Harry has, so he's had plenty of opportunity to play that protective older brother without Harry knowing or noticing. So here's what I want (yes, it's another 5 and 1):
Five times Thomas chased off Harry's potential boy/girl-friend, and one boy/girl-friend he missed.
Thomas Cock!Blocking
Five times Thomas chased off Harry's potential boy/girl-friend, and one boy/girl-friend he missed.