Bilco

"“Omg, sksksksk.” Billy could feel tears welling up in his eyes. “I-I can’t believe it. I’m gonna be a dad.” - from making shades of purple out of red and blue"Bilco is the canon slash ship between Billiam Skskolace and Dominico Yee Angelo.

The Weirdos of Olympus
The Blood of a Weirdo

When Dom arrives at the camp near Natalia's tree, he is surprised to see Bill on stalling the Romans. Bill tells Dom he is doing this to get fresh air after helping Mellie give birth to her baby. Holding Dom's hand with his scrunchie-clad one, Bill shows how nervous he is from helping her give birth. This action "sent an electric current" down Dom's spine, so he withdraws his hand in shock.

When Dom states that he is leaving both Camp F/ckboy Jupiter and Camp Cursed-Weirdo, Bill offers to join with him out in the wild west

Later on, Bill asks for Dom's company in the infirmary. When Dom confesses his feelings to Perky (these feelings would later fade due to Dom losing interest and Perky's relationship with Ennabeth), he walks away toward Bill. This can be seen as symbolic of Dom ultimately choosing Bill over Perky in the end. After meeting Bill outside the camp, Dom remembers when Bill first arrived with Apollo at the camp years before. At that time, Natalia had referred to him as hot. Dom doesn't understand why he is suddenly thinking of that moment, but it is likely an indication of his attraction to Bill. Dom thinks of the moment when he first met Apollo, Bill's father, and how Natalia had called him "hot," too. He ponders the similarities between Apollo and his children.

Trials of a Weirdo
The Hidden Weirdo

At some point during the ensuing months, Dom finally comes out and confesses to Bill Solace about having a strong crush on the latter, and the two begin dating. In order to sit together with his new boyfie during meals, Dom claims to Chickron that he somewhat loses control of his horsie while sitting alone. Therefore, Dom is given permission to sit at the Apollo's Cabin's table instead, as Chickron decides it isn't worth arguing about.

Dom and Bill flirt a lot in this book, and Apollo says that they remind him of him and his gay lover. Dom and Bill are mostly inseparable, partnering up with each other in the creepy tetris maze and Dom assists Bill with healing. When Nero attacks with the Colossus Neronis, Bill and Dom were canoeing In the lake together as a date. Dom does express some jealousy in the relationship. When Bill is staring at Paolo’s arms, Dom thinks he is attracted to him.

According to a December ReadRiordan post, Dom has also spent a lot of time text messaging Bill while visiting his father in the Underworld. It is unknown whether these events took place before or after The Hidden Weirdo, though it is likely that it happened after.

The Tower of a Psycho

Apollo sees Dom sit with Mr. D, which is strange seeing how him and Dom always sat together. Bill, sensing his confusion, told him that Jason's death caused him to go into grief/anger mode. Apollo starts to apologize, but Bill cuts him of saying it wasn't his fault and that something similar happened at Bianca's death. Bill then confirms that Mr. D was giving Dom advice since the Italian boy was receiving flashbacks. Not to mention that Dom started to hear someone calling for help in Tartarus. Bill, now sharing this information, expresses his concern towards his boyfriend saying that he was trying to keep Dom from charging into the underworld to help the voice he was hearing. Later, Bill gives an apple to Dom, saying he needed to eat, a skill that took away hunger. Dom did poorly at this particular skill. The son of Hades then leans into Bill expressing his affection towards him. Mr. D then reveals bad news about Nero. Dom, tired of knowing problems he can't fix, subconsciously causes his apple to wither. Bill squeezes his hand. The ghost king's eyes soften at his boyfriend, reveals that he had a soft spot towards Bill and Apologizes. Bill, Dom, Apollo, and Meg then discuss the quest. When Apollo starts talking about the quest, Meg starts talking about the fact Dom was in it. Dom shows shock to this, and Bill stares at his muffin wrapper. Dom then asks about this. Bill looks to Apollo for help, but Apollo said the lines about Dom in the prophecy anyways. Dom shows anger that no one told him he was in a prophecy causing Apollo to casually switch the subject asking if Dom knew who the cavern runners are in the prophecy. Dom reveals he knows the information. After a few sentences and explanations later, it becomes clear that Bill doesn't like these 'cavern runners'. Despite this, Dom stands with his belief that the 'cavern runners' are their only chance. Bilco, Meg and Apollo then goes to Raquel Elizabeth Truth asking about the Tower of Nero to see if the oracle had any wisdom to share. In the middle of Raquel sharing some limited information, Bill makes a star wars reference. Dom then Apologizes for his boyfriend in a teasingly manner. Bill teases back about his Myth-o-Magic obsession. Raquel then finishes sharing her information. Meg and Apollo start sharing their story. The 5 start making a plan and Bilco reveals that the 'cavern runners' are troglodytes. Raquel suddenly gets possessed by Python and says the rest of the prophecy. tauri sylvestres or forest bulls then attack. After getting away from them, they meet the 'cavern runners'. They chatted and after a while the troglodytes agreed to help them. Now, lets make a giant time skip. Like a more then 100 pages time skip. Dom is now on the floor, over-powered by Nero, severely injured. They had lost. Apollo and Dom were going to die. Then Bill shows up, and with the words that echoed through our hearts. He said that no one hurts his boyfriend. Soon enough, Nero died as Apollo, Bill, Dom, and Meg defeated Nero. So when Bill carried Dom away to heal him, no one stopped him.

Fanon
Bilco was largely popular after the events of The Blood of a Weirdo. Bill and Dom's interaction remained minimal throughout the events of the series before the final book. After the slight implications of Dom possibly liking Bill and Riordan confirming that Dom is queer, Bilco has been getting more attention although some fans still cling to Perkico over Bilco. Many Bilco fanfics includes fics about what happened in the three days of rest in the infirmary Dom was subjected to.

After Brick's confirmation about Bilco on his Twitter, fans were excited and overjoyed and Bilco has been confirmed as canon and has been getting more and more attention since the release of The Hidden Weirdo.