Despite the fact that Fang openly despises Sherman, the latter shows no harsh feelings towards Fang, and treated him like equals. In the Hot Spring event, Sherman even stated that Fang is a good person deep down, despite his demeanor, much to Fang's embarrassment.
However, after the singularity in the Goddess route, Sherman finds Fang to be his adversary towards his goal in reviving the Vile God, and will stop at nothing to eliminate Fang.
As Sherman retains his personality from the previous timeline in the Vile God route, he and Eryn believed that Fang is the only Fencer who can defeat the Vile God. During the time that Fang is absent, as well as being an amnesiac, Sherman acts as the de facto leader of the group until Fang recovered his memories via the Goddess's power. While Fang's animosity towards Sherman remains, the two seem to be on slightly friendly terms ever since. After noticing how Fang decided to spare Paiga, Sherman realized that he does not have to kill Tiara to follow the path of justice. . Ultimately, Fang's heroic deed is what made Sherman change his goal in achieving world peace, this time without killing anyone who has a chance of redemption.
Sherman firsts meets Tiara at the Dorfa Corporation's Party and was praised by her on his talent playing the piano. The second time they encountered one another was when he saved Fang's life at Kidanar, as he gives the fury to her, he was then inquired by her asking him what does he plan to wish for. He responded with world peace, learning she shares the same wish he states it warms his heart. He encounters her at the Zawaza Plains where he then joins the group. On the night before the group heads out to the Subterranean Tower, wanting to grab a drink of water, he spots Tiara's hand bag, and wonders why was it left here. He decides to return it upon coming to close to her room, he overhears Tiara praying to the Goddess. Touched by her sincerity, it was here where Sherman started to fall in love with Tiara and wanted to make her happy. He decided to go and purchase an engagement ring while the group headed out to their destination. After defeating Bernard, the group decided to rest for the night. Depending on which girl Fang talks to, Sherman will appear worried if its Tiara, Fang is talking to. He then calls Tiara to meet him in private away from the group camp. He then confesses that this is the first time he's fallen in love, however jealousy sweeps over him once she mentions Fang. Causing him to ask her to pay attention to him, and tries to make her take his ring which causes Tiara to panic and asks him to stop (In the original PS3 version, it was implied he was forcing himself onto her). He lets go of her once he spots the mark of the Vile God on her forehead.
In the Goddess Route, he ends her life with her permission. This causes him to become mentally unstable as his love for Tiara, his hatred for the Vile God, and his guilt for killing her corrupts him. He travels back in time with Fang and Eryn. Whenever he spots her, he often holds a look of contempt in his eyes, and asks her to realize his dream with her together by reviving the Vile God as its shown he is still in love with Tiara however in a more corrupt tone.
In the Vile God Route, he doesn't kill her, and is implied to still have feelings for her as his fairy partner Ryushin mentions that his body temperature and heart rate rises from the thought of Tiara as he prays that her fate with having the Vile God's blood isn't carried over. After encountering her again, Sherman manages to convince her to join the group by offering to pay her meals with his money. He is later seen with having to often restraint her by threatening to no longer pay for her room and meals which mostly works. After Tiara gets kidnapped, he starts to question his ideals to the point of deciding he will no longer kill her and is determined to save her. Once the Vile God is defeated, their relationship is unknown in the epilogue of the route.
In the Evil Goddess Route, he is seen worrying about her, and crying over her death, asking himself if this what was fate in store for the two, and wishes strongly for a world filled with justice and beauty because of it. After drinking the wine, he seems to have stopped caring about Tiara and wants her dead forgetting that the Vile God is dead in the new world he created.
Their relationship varies between routes, as in the Goddess Route he attempts to end Apollonius's life after Fang and the others defeated him, and his blow had he not been pushed would of been fatal. In the Vile God Route they're seen as comrades in arms as Sherman's words and prowess with a blade made him decide his life was worth living for and follows him. In the Evil Goddess route, it is unknown whether or not it was Sherman that offer him employment for the Septerion Club.
She was his secretary in the Evil Goddess Route, and noted that she reminds him of his sister when he looks at her. While it is unknown if he was aware of her romantic feelings towards him, he cares about her, and is seen in despair as he watches her die after sacrificing herself for him.