Many different characters in Stardew Valley serve a lot of different purposes. One of those characters is Sebastian. He is one of 12 characters that players can marry in-game. Here's the complete guide to Sebastian in Stardew Valley.
Stardew Valley Sebastian: A guide
Here's what the game's developers had to say about the character:
“Sebastian is a rebellious loner who lives in his parents’ basement. Maru’s older half-brother feels like his sister gets all the attention and adoration while he is left to rot in the dark."
"He tends to get deeply absorbed in his work, computer games, comic books, sci-fi novels, and will sometimes spend great lengths of time pursuing these hobbies alone in his room. He can be a bit unfriendly to people he doesn’t know. Could a charming new farmer cultivate the wasteland of his heart? Who knows?”
Sebastian is one of 12 characters that can marry players and lives in the mountains north of Pelican Town. He lives in the basement of his mother Robin's carpenter shop. He lives with his mother, his stepfather Demtrius and half-sister Maru. He is good friends with other Stardew Valley NPCs, Abigail, and Sam.
Sebastian can be given two gifts per week and once on his birthday to increase the player's relationship with him. He loves frozen tears, obsidian, pumpkin soup, sashimi, and void eggs. He likes flounder and quartz.
He dislikes chanterelle, common mushrooms, daffodils, dandelions, ginger, hazelnuts, holly, leeks, magma caps, morels, purple mushrooms, salmonberries, snow yams, wild horseradish, and winter roots. Sebastian hates clay, complete breakfasts, farmer's lunch, and omelets.
Sebastian can be interacted with and given gifts to increase the relationship, which will, in turn, change his behavior and activities. The more he likes a gift, the more it will increase the relationship with the player. This will be measured in hearts.