During the live chats, after having fans using the term Starco, due to Star and Marco unaware of the term, the pair believes that “it’s probably just a way of putting our names together so it’s faster.” As the episode ends the Blood Moon is shown in the sky symbolizing their bonding of their souls. At the end of the episode Star is shown quickly grabbing the reel of photos which shows Star and Marco's cheeks are glowing. In the final reel, Marco turns to look at Star, she returns his gaze, and they kiss, meaning that Star has cheated on Tom. With the money they have left, Marco says he knows what kind of photo the booth wants. They sit in silence before joking about how their guts feel, and Marco admits he feels better having talked about it. Star is unsure what he means, but when he says things are different for him specifically, Star realises he's now confessing his feelings for her. Despite his efforts to not think about it again, he says he can't keep pretending things aren't different now.

In ' Booth Buddies' Marco relents and explains that the real difference between the past and present photos is that the past photos were taken before Star's confession in 'Starcrushed'. After the events of Lava Lake Beach, Star and Marco's friendship is seen to come to a strain. In ' Lava Lake Beach', after having a talk with Tad, Marco realises that he has feelings for Star, but feels that he may be too late because Star is in a relationship.

In ' Sophomore Slump', Jackie sees him still being attached to Mewni and breaks up with him, realising that his friendship with Star is more important than their relationship and that he would be happier in Mewni than in Echo Creek. In the following episodes, Marco comes to live on Mewni after not being able to adjust to life back on Earth and let Star go. After that, Marco returns to Earth as he and Star part ways.

He goes to Mewni to find Star as she went back to Mewni and he helps in the battle against Toffee.

Then after that in ' Starcrushed', Star confesses her crush to Marco after Toffee returns but Marco doesn’t have a chance to respond before she flees the room, so his thoughts are currently unknown. Additionally, Star became extremely jealous when Marco and Jackie went on a date in 'Bon Bon the Birthday Clown' to the point where her spells went out of control, further showing Star's true feelings for Marco. In the episode ' Blood Moon Ball', Star and Marco's souls were joined under the light of the Blood Moon, which, according to demon lore, 'selects two lucky souls, binding them together for eternity in its hypnotic, ruby brodum.' Episodes ' Sleepover', and ' Bon Bon the Birthday Clown', both confirmed that Star has a crush on Marco, but Marco doesn't seem to reciprocate her feelings.

Conquer star vs the forces of evil