Tatiana was a female tiger who was intended to have been a childhood love-interest of Antoine D'Coolette appearing only in Sonic the Hedgehog #137 in the Sonic the Hedgehog comic series published by Archie Comics.
Her story is unveiled as a flashback-within-in-flashback. Supposedly, she had agreed to go on a date with the "heroic" Antoine only to be told by Sonic that everything she heard about Ant was a lie. Afterwards, she told Ant that she no longer cared for him and was seen walking off hand-in-hand with Sonic while Antoine privately vowed never to fall in love again (until he met Bunnie). She moved away shortly thereafter and was not seen or from for years until she wrote a letter to Antoine asking to meet with him again. Antoine became nervous since he was now dating Bunnie, and when he told Bunnie of his dilemma she seemed resigned to let Antoine date Tatiana. However, Antoine publicly refused Tatiana's advances and acknowledged his preference for Bunnie's affection. Bunnie writes a letter thanking Ant for his decision declaring that while she was afraid to admit she loved Antoine then, she is afraid no longer. The story concludes by returning to the present day where Antoine rips her letter to shreds.
Tatiana's back-story contradicts with several elements of the established canon: Antoine had been betrothed to Princess Sally since his youth (although Sally herself did not learn of the arranged marriage until Sonic the Hedgehog #160) and much of the first forty issues of the comic depict his efforts to win the Princess's heart; hardly the actions of a man who had sworn off romance. Young Antoine describes himself as a Freedom Fighter, a term coined by Sally while the children were living in Knothole. For nearly a dozen years Knothole was the main place of refuge from the threat of roboticization making it unlikely that anyone could or would move away from there.
Despite the story's assertions, Bunnie was never afraid to admit her feelings for Antoine, in fact she spurred on the romance in Sonic the Hedgehog #46 by kissing a surprised Antoine on the cheek while telling him how much she cared. The story also describes Tatiana's return to Knothole as taking place shortly after Endgame (when Antoine and Bunnie were a new couple), yet the art shows Bunnie with her post upgrade limbs and chin-length haircut which indicates a much later timeline. Further complicating matters, Sonic the Hedgehog #150 revealed that Patch began masquerading as Antoine during Sonic's one-year-absence and could not have access to such childhood memories as the characters grew up in parallel dimensions. It is possible that Patch fabricated part or all of the story while researching his role as "Antoine". (Issue #168 would lend motivation to this theory, as Bunnie and Antoine discuss the severity of Patch's actions, Bunnie suggests that Patch may have gotten a thrill out of his attempts to destroy everything Antoine loved.)