What are traits of M&M from That Was Then, This Is Now?

M&M is Cathy Carlson's 13 year old brother in S.E.
Hinton's teen novel That Was Then, This Is Now. M&M gets
his nickname from his love of the candy of the same name. Unlike Bryon and Mark,
M&M is a young hippie: He has long hair and wears an old army jacket with
a peace symbol hanging from his neck. He seems to be popular with just about everyone
except his father, who nags him relentlessly about his bad grades. Bryon particularly
likes M&M because Bryon is interested in M&M's sister, Cathy.
M&M likes smoking pot, and he eventually runs away from home, ending up in a
"hippie house," where he is given another nickname, "Baby Freak." He eventually turns to
LSD. Bryon and Cathy finally locate him at the house, where he is suffering from a
particular bad trip in which spiders have been eating at him. The bad trip has a lasting
effect on M&M: His grades have gotten worse and he has memory
lapses.