Jumpy and nervous twenty-gour seven but, not weak at all.

Sure, Johnny was jumpy and startles easily but he wasn't weak. If anything the boy had slight anger issues but kept quiet for the most part.

The gang had seen him snap a few times. One time Two-Bit was messing with him while he was tired and he snapped at him. Another time was Dally messing with his hair. Each time the guys were always shocked, even Johnny was then he'd go back to being quiet.

So yeah, he's quiet and jumpy like all the time but, god, the boy has a temper and a mouth. Partly from hanging out with Dally so much and shit but—Whatever.