[NOTE: I'm mostly following cartoon canon even though he didn't really figure in the series. He was in the cartoon towards the end of its run [just before or after cancellation], but that cartoon was not broadcast in North America—to my knowledge.
UPDATE [12-22-07]: It's been decided that Rad is essentially an amalgamation of various elements from the G1 canons [comics old and new, and the cartoons], and will incorporate them all, as long as they don't contradict each other.
Also, for him it's now the middle of 2006. Rodimus is just completing his first solar cycle [that's a year to us fleshlings] as the new Prime of the Autobots. So there'll be references to recent history [which I will add as having occured in his world—again, provided it doesn't contradict canon] now and then.]
For someone who's talented as a marksman and a scholar-scientist [being one of the better mechs in both disciplines], he's quite a modest, polite individual. Never crass unless he's really lost his cool or if Lionizer is proving to be a particular handful that solar cycle, he's an easy-going, well-spoken mech that most people like to have on their team, and is often considered very approachable by humans who know their Cybertronians. To Daniel Witwicky he's almost what humans would call a "cousin", and he regrets that duty often sends him halfway across the galaxy, instead of allowing him time to mellow out with the Witwickys themselves.
Rad is also a 'bot who knows his limits. Becoming "Prime" or even a prominent leader doesn't interest him, though his judgements in various areas are often sought out by others—[sometimes he just wishes that they'd make their own minds up!]—others who insist he'd make a fine "Prime" if he wanted to be [and he doesn't]. As it is, he figures that Rodimus is doing a fine enough job, despite the sudden assumption of leadership by the young Autobot.
He'll just be one of the soldiers, lending a laser in the fight against the Decepticons...
Rad and Lionizer are from the Transformers franchise [specifically Generation One], and is the property of Hasbro/Takara/IDW-Devil's Due Publishing/etc. They appeare here solely for the purpose of role-playing in milliways_bar, from which no profit whatsoever is being made.