In an alternate universe, Thanos and Agatha Harkness were a couple. Thanos was still determined to balance the universe, but with Agatha by his side, he found himself second-guessing his methods. Agatha was a powerful witch, and her magic often clashed with Thanos' brute strength.
Their relationship was tumultuous, but they couldn't stay away from each other. Together, they wreaked havoc across the galaxy, leaving destruction in their wake. They fought the Avengers and the Guardians of the Galaxy, but their love for each other was stronger than any foe.
However, their love for each other also led to their downfall. When Agatha cast a spell to bring back her deceased son, she inadvertently opened a portal to the multiverse. Thanos, seeing this as his opportunity to bring balance to all realities, jumped through the portal, leaving Agatha behind.
As he traveled through the multiverse, Thanos found himself confronted by countless versions of himself, each with their own ideologies and methods for bringing balance to the universe. Meanwhile, Agatha was left to deal with the chaos Thanos had unleashed in his wake.
In the end, Thanos realized that he had been chasing a false ideal of balance, and that true balance could only be achieved through love and compassion. He returned to Agatha, and the two reconciled, deciding to use their powers for good instead of destruction.