Some TMNT stuff really isn't for little kids.
Tommy is a recurring character in the IDW continuity. He is one of the children of St. Robert's Orphanage. The orphans were originally rescued from death at the hands of the Rat King during the Kingdom of Rats story arc, and because St. Robert's Orphanage had been destroyed during the EPF-Triceraton war, found a new home at Foot Headquarters. In an agreement between Splinter's Foot Clan and the Turtles' Clan Hamato, the orphans would be wards of the Foot Clan but never be forced to formally join them, and Clan Hamato would train them in ninjutsu under Michelangelo's instruction.
But Tommy as a distinct character did not appear until Teenage Mutant Ninja Turtles #89. He is an ordinary, easily excited human little boy who looks up to Mikey, Jenny and Splinter as influential grownups, and refers to Master Splinter as "Mister Spinter." Tommy is the first of the orphans to appear by name in more than one issue.
In TMNT #89, on Christmas Eve, Jennika meets Splinter in his room to report that the children are all sleeping the night. Jenny is forced to eat her words as Tommy rushes into the room, saying that he heard Santa Claus. Splinter admonishes her chūnin for letting young children roam around Foot HQ unescorted. As Jenny picks up Tommy to carry him out of the room, Tommy gawks at Splinter's appearance, remarking "He gots whiskers." At the end of the issue's story, after receiving visits from an old friend's ghost and three members of the Pantheon, Splinter throws a Christmas party with the orphans, his own sons and several of their human and mutant friends. They arrive to see Splinter dressed as Santa Claus and Tommy sitting in his lap holding a Christmas present.
In TMNT #90, Tommy interrupts Splinter's meditation to tell him that the kids don't know how to operate the old-fashioned videocassette recorder. Mikey and Jenny usually operate the VCR for them, but neither is there. In a moment of fond reflection, Splinter tells the kids present about Michelangelo's film collection and views on martial arts archetypes in film. The moment is interrupted by the unannounced return of Oroku Karai and her subordinates after their long absence since the Vengeance story arc.