You young whippersnappers!
Jetfire is a cranky old giant robot transformer who hates kids on his lawn. He likes commanding inanimate objects to do things and then blasting them when they don't. He's also confused over what side he's on in the transformers war.
He hates everyone and everything unless they are the government. And in transformers terms, Optimus Prime is the government. Jetfire also likes playing golf, watching paint dry and eating nuts and bolts. Yum?
Jetfire transforms into an SR-71 blackbird, which would be a stealthy plane if it didn't spew black smoke across the landscape. Jetfire dealt more than enough pain during the war, and claims that no-one knows how to bring the pain, like they did in 'his day'.
He also beats other transformers to death with his walking stick, which is probably why he was abandoned in a museum.