Trunks had enough of Cosmos, being just a friend. He stole a kiss from her during a debate over the planet's protection.
The kiss got more heated, leading to intimacy. That night, Trunks claimed Cosmos as his mate. He bit into her neck.
Cosmos woke him up with a surprise. She was licking his neck, in a seductive manner. Trunks woke up with a grin, flipping her over to her back. Cosmos magically made their clothes disappear. Trunks shoved a muscular thigh between her legs. He pressed his knee against her clit, rubbing the moist flesh to sensitivity.
He licked around her breasts, until the nipples became hard pebbles. He then suckled her tender breasts, causing her to arch her back in pleasure. He pressed down on her body, forcing her to lay back down. He gradually increased the pressured from his mouth on her breast. She gasped for breath, using her hands to rake her pink nails down his back- causing a masculine groan. She squirmed wanting the complete connection of bodies.
Trunks growled at her movements. Cosmos just grinned. A Vegeta-like smirk graced his features as he rubbed his engorged cock against her clit, getting her to moan.
He slid into drenched cavern in agony as his cock throbbed, demanding release. Cosmos met him half way each time he'd thrust into her vagina. His pelvis rubbed her sensitive flesh down under, causing her to tremble as her climax was fast approaching. Her cavern squeezed his thick penis as she came in a massive orgasm, uniting them in pleasure as he orgasmed with a deafening roar. His hair turned blonde momentarily as he orgasmed. Shortly afterwards, it went back to lavender.
Trunks pulled her into his arms as he rolled onto his back. She fell asleep listening to his steady heartbeat.
The next morning, they discussed marrying. They decided to do it in the past and present. As Cosmos stepped out of her portal, Piccolo attacked her without warning. Trunks growled as his animal side emerged when he saw her attacked then he beat Piccolo to a pulp. The rest of the Dragonball Z gang arrived, scaring Cosmos even more.
She ran, thinking they were barbarians for attacking someone without reason. She took several portals to lose the big burly men.
"I promised her that she would not have to fight if she came. She only fights for justice so she wasn't going to attack. Damn it, she bounced around to hide her trail." Trunks paced around thinking of where she could be.
"Calm down to tell us who she is. I couldn't feel her ki at all," soothed Goku.
"Being Lunarian, her ki is masked completely. However, don't let that fool you. She is an immortal goddess named Serenity Hikari Cosmos, Queen of the Stars and Empress of Light."
"Stop fooling around, boy. She is lying to you," growled Vegeta.
"You are wrong," muttered a wounded Piccolo.
"Huh," everybody blinked in confusion.
"She is Queen Serenity Celeste Moon and King Tranquility's daughter. She is favored by Hera. She has domain over all light sources. She is Sailor Cosmos, the ultimate being of purity. Cosmos, frees the oppressed..."
"Enough, I don't feel like hearing all her honors and more again," Trunks put a stop to it. "Simply put, she is my mate and intended. I love her with all that I am. That should be enough."
After a week of searching, Trunks carried his weary lover back to Capsule Corps. She was sheltering at a spa on Delta Capa. They fell asleep in each other's arms. Cosmos put a silencing spell on the room.