June 20th excerpt:

This movement caught Dean off guard, and left the smaller man clinging to the curls in surprise. “What did I say about movin?’ “ he scolded, frozen in place until he was absolutely certain Sherlock wasn’t going to knock him off. “This is hard enough already! I’d like to see you climb someone’s hair.”

Taking a deep breath to steel himself and forcing any thought of how high up he was suspended in the air on a moving person, Dean started to climb again.

Only now, he put more effort into where his boots dug into Sherlock’s scalp. 

For traction.