Captain America and the Scarlet Witch are longtime friends and teammates on the Avengers. The two heroes have spent many years together, forming a close bond, and they almost developed one of the weirdest superhero romances in the Marvel Universe.
In 2004, this surprising relationship emerged in Captain America and the Falcon #6, by Christopher Priest and Joe Bennett. While Captain America and the Falcon were on the run from the U.S. Government, they were saved by their fellow Avengers, Hank Pym's Yellowjacket and the Scarlet Witch. During this encounter, there was a surprising flirtation between the Captain and Wanda, as the Scarlet Witch told Steve Rogers that she always admired him.
As things began to heat up between the two Avengers, Yellowjacket interrupted with more pressing matters. Steve later began to experience intense hallucinations. Captain America relived the death of his partner Bucky and being frozen in a block of ice before returning to reality. Once there, the Captain admitted to the Scarlet Witch just how exhausted he was. Finally, the two of them shared a kiss.
At the beginning of the next issue, Wanda was revealed to have slept on Steve's couch. Although Captain America insisted that they didn't sleep together, his relationship with the Scarlet Witch took a more serious turn. Wanda admitted that things were different between them. While before, Steve saw an "exotic child," their kiss drastically altered the Avengers' dynamic.
Given Wanda's age, Steve was very hesitant about developing a relationship with her, although Wanda reasoned that Steve was much older than most women anyway. The Scarlet Witch told Captain America that love wasn't convenient or logical, convincing him to kiss her again. During the same issue, Captain America hallucinated about Bucky's death again, along with his discovery in the ice by the Avengers. This episode ended with Steve fantasizing about Wanda. When talking to the Falcon, the Captain confessed that he hoped to have feelings for the Scarlet Witch. Right before Iron Man's UN address, Captain America went to see Wanda again. Telling Wanda that he thought about what she told him before, Steve said that he was willing to give their relationship a chance.
Wanda, however, had no idea what Steve was talking about. Furthermore, the Scarlet Witch told Steve that his words were inappropriate, even questioning his sanity. With this, the Scarlet Witch walked away, leaving the Sentinel of Liberty extremely confused.
It wasn't until the events of "Avengers: Disassembled" that the truth behind this encounter was revealed. The Scarlet Witch was undergoing a nervous breakdown, one which affected both her sanity and her magical powers.
This explosion of magic explained the hallucinations that the Captain had earlier, as well as his unusual feelings and unstable emotional state. Captain America may have had feelings for Wanda that he never expressed or realized, so Wanda's breakdown might have exploited and amplified these feelings.
Wanda's breakdown also explained her mental lapse. For one thing, it was very unlikely that the Scarlet Witch would suddenly develop feelings for Captain America. In all likelihood, she also harbored some undisclosed feelings for Steve that she never acted on.
By the end of "Avengers: Disassembled," the Scarlet Witch and Captain America had narrowly avoided one of the oddest relationships in the history of Earth's Mightiest Heroes.