Whether or not he's a prick remains to be seen.
|“||Prowl to Prime aboard the Ark-The Reign of Starscream Issue Number One.||”|
—You turned death into a fighting chance to live!
Before the war, Prowl was a member of Cybertron's security forces. When Optimus noticed an odd change in behaviour from his brother, he enlisted Prowl's help to break into The Lord High Protector's quarters along with him and Jazz. When asked why he was taking so long, Prowl commented that it had been a while since he had broken into a superior's quarters. In it, they found the strange artifact that Megatron had ordered brought to his quarters. While Optimus was looking at the artifact, Prowl received a call from Skyblast that the battle was over and Megatron was returning. Prowl received orders from Lord Protector Megatron to arrest Optimus Prime for treason. Prowl led Jazz, Camshaft, Bumblebee, and Smokescreen to take Prime and his squad into custody. However Prowl was uncomfortable with the level of Megatron's information. A concern that proved well founded when he was the first casualty of a trap laid by Megatron.
Prowl survived the assault and joined Prime's Autobot faction, where he seemed to work in a strategic planning role, advising Optimus on intel. Prowl fought alongside Optimus at the Temple of Simfur, handily dispatching an opponent with each hand.
Prowl was aboard the Ark when the vessel was being readied to launch and intercept the All Spark and Megatron. While Optimus felt guilt over his decision to send the All Spark into space, which would ultimately doom Cybertron, Prowl said that the act changed the Autobots' situation from certain death to a fighting chance.
Prowl was originally intended to be in the live-action movie as part of the Autobots' original line up, but the writers liked the idea of an evil police car so much that Prowl was cut.
Better luck next time.
Or next time. Nevermind.