Hartmut

Hartmut (ハルトムート Harutomuto) is a noble child Rozemyne meets in the playroom. He is part of the Leisegang faction and Ottilie's youngest son

Hartmut fully buys into the legend of the "Saint of Ehrenfest" and is very devoted in futhering it's spread, much to Rozemyne's annoyance. After some initial hickups, she manages to restrain his activities somewhat.

At Rihyarda's recommendation Rozemyne decides to choose him as one of her retainers upon her entry into the Royal Academy.

Without knowing about Rozemynes intentions or wishes he takes it upon himself to work on making her the next Aub Ehrenfest. When Rozemyne learns of this she tells him outright that she has absolutely no intention of becoming the archduchess and that he sould cease all his effort to bring this along.

Spoiler for Part 4 Volume 2 Hartmut stops actively working to get Rozemyne elected as the successor, but still can't stop himself from constantly talking about how great she would be as the archduchess in private.

He has a tendency of keeping his information to himself until he deems it most useful to release it, even keeping it from his mistress. When Rozemyne calls him out on this and tells him to tell her everything he uncovers without holding anything back, he seems genuinely surprised for a moment, hinting that he did this more out of instinct rather than a lack of trust in Rozemyne's judgement, before vowing to devote himself to her better in the future.

He is very impressed with how Rozemyne managed to find a truly optimal way of dealing with Traugott in a way that caused the minimal amount of problems and hurt feelings, while at the same time maximizing the benefit to her and her allies.

While Rozemyne is back in Ehrenfest for the Dedication Ritual it falls to Leonore to keep Harmut from letting his enthusiasm from getting the better of him, since even Hartmut's own mother Ottilie worries greatly of exactly this happening and asks Leonore to keep an eye on him in Rozemyne's absence.

Spoiler for Part 4 Volume 2 While his full set of elemental affinities is not known, it is known that he has an affinity for Light, but no affinity for Darkness.