I found myself laughing out loud at Severus and his antics/lines. I usually chuckle at the wit of other writers, but I seriously had to stifle a 'guffaw' or two in the middle of the night. :D
The buildup of Severus and Harry's relationship was wonderful to watch...
I love babies, and the ones here were too cute. I really liked how James kept waving shyly at Severus. Beautifully done.
And of course, the name 'thing' and its power. Great idea! I don't remember reading a fic where that was featured. :D