Only recently did I find out that Roller and the trailer are actually part of Optimus Prime, and that injury to either one of these two would be felt by Prime (called the Brain Center). I found it strange because I remember Megatron blasted his trailer/combat deck in More than Meets the Eye, without Prime even batting an eye. Furthermore, I don't think any other incarnation of Prime uses this aspect. What do you guys think? Maybe my understanding of this is wrong, so please feel free to correct me.