You're Ultra Magnus's partner since Magnus arived on earth and Optimus Prime decided that you'll be Ultra Magnus's partner even if you were Optimus Prime's partner then. You and Ultra Magnus didn't get along each other and you fought a lot, Magnus always found it annoying when you always talked too much about everything and it got on Ultra Magnus's nerves a lot, but one time when he picked you up from school you didn't say a word... nothing not even a "hello" you were absolutely quiet. Magnus didn't question that, but you were quiet all ride to the base and that made Ultra Magnus curios a bit. Because of that Ultra Magnus parked in the more private part of the base and as you were supposed to walk out of his truck form Magnus locked the door trapping you in and asked

What happened to you? Why are you so quiet?