FIVE HAD PTSD FROM BEING TRAPPED IN THE APOCALYPSE FOR YEARS, so he usually had hallucinations. Which made him scared and always so skeptical about everything, especially getting close with someone ; he always randomly comes and put his fingers on your pulse point for those reasons, to reassure him that you were real. He never told you why he does it, but it was for the better.

He was standing next to you, staring at you before he suddenly moves two of his fingers up to your pulse point.