From what we know, Ravage is like Soundwave's pet cat from the G1 cartoon. And from robot chicken it seems that he cares for his cassettes, remember Rumble or Frenzy I can't remember who. Ravage appeared in Revenge of the Fallen then Bumblebee ripped his spine out. My point is, after Bumblebee killed Soundwave's cat, do you think he held a grudge on Bumblebee, then in the hostage scene, Soundwave was about to avenge Ravage, because it looked like Soundwave wanted to be the one to kill Bumblebee. But then failed.