Hello, thank you very much for playing! We had fun with making this game and I'm glad other people are left with a wish to interact with the characters more. Hopefully, something will come in the future!
As for the endings, Tamas and William are the only two guardian options, but there is a chance that, even picking William, you will not succeed in gaining him as Mawla. Essentially, you can a) pick Tamas; b) pick William and get William; c) pick William but, due to choices in the flashbacks, get Tamas instead. The main way to reach this ending is by selling William to Tamas and by giving Tamas information on the Voice; the more Tamas knows, the more likely that he will be able to convince the Prince that he is the right guardian for Florian during the confrontation in Elysium. In this ending, flavour text changes and Tamas picks a different location for the Thinblood brand during the branding scene.