Headstrong is a Decepticon.
When the Quintesson-ordered peace talks between the Autobots and Decepticons broke down on Aquatron, most of the ground parties were captured, including Megatron. Starscream returned to the Nemesis and tried to seize control, but Soundwave refused to leave without Megatron. Starscream stalled by ordering increasingly pointless scans of the area to "prepare" for a rescue mission. Eventually, Headstrong and group of Decepticons stormed the bridge and threatened mutiny to force Starscream's hand and get the rescue of Megatron underway.'