Jörmungandr wasn't good with reading mortals, but he could read his siblings rather well. And while Hel didn't want mortal friends, he did want her to be happy. He wasn't ever sure if she was.
It didn't stop him from trying to make her happy though. So he crossed the apartment to come up behind her and hug her. He was learning how much pressure his siblings could take. Mortals were still tricky, but his siblings were used to it.
"You should come sleep on the rock Little Hel," speaking in their native language was so much easier then English. English didn't make him look clever, and he was just as smart as his siblings. "The view is nice now the leaves are all different."