The phrase "a sidekick in" is correct and usable in written English.
It can be used to describe someone who assists or accompanies another person, often in a supportive role, particularly in contexts like storytelling, movies, or games.
Example: "In the latest superhero movie, the main character had a loyal sidekick in a witty and resourceful friend."
Alternatives: "a partner in" or "an accomplice in".
Mr. Letterman chose not to have a sidekick in the traditional sense.
She is like all of us: human, not a flat stereotype or a sidekick in someone else's story.
A sharp lament about being a sidekick, in life and in musicals, is sweetly delivered by Georgina Hagen.
I'm a capable person too, and I knew it would drive me mad just to be a sidekick in a parish church.
I wonder if it happened in the lobby, where a skinny bored girl in what might be her underwear lounges, text-messaging on a Sidekick, in a glass tank above the reception desk.
He has a preppy orange jacket and close-cut hair in the "Wes Anderson" remake; hipster sideburns in the "Joe Swanberg" version; and a talking meatball sandwich for a sidekick in the "David Lynch" one.
His new roles included a servant subjected to the screaming racial abuse of Lionel Barrymore, a snivelling sidekick in a John Ford movie, and a butt of amiably insulting jokes for Will Rogers — and all the while he was becoming ever more absurdly stylized, his high, whimpering speech nearly vaporizing into the musical spheres.
Ethan Lipton, a wry singer-songwriter whose heavy-lidded affability and retro facial hair make him look like a doomed sidekick in a '70s cop movie, grinned upon learning that one collaborator after another had independently used the word Everyman to describe him.
He will meet up again with Marion Ravenwood Karen Allenn, back for the first time since the franchise launched with "Raiders of the Lost Ark" in 1981) as well as a young sidekick in a 1950s greaser named Mutt Williams (Shia LaBeouf).
We have Lund, desperate to leave the department, forced into investigating a daughter taken from a family, with a new sidekick in tow.
He was 20 then; now he has a sidekick (Warren Oates) in tow and avengers on his tail.
