In the past, Clind trained Frederica to help her control her beast form. Following the events of Arc 4, he was brought into the Emilia Camp by Roswaal to oversee Subaru's training after the boy officially became Emilia's knight.
Despite being at least 400 years in age, Clind appears to be a handsome young man with a slender face with a tall, lean body. Along with that, he has eyebrow length blue hair. Clind wears a well-starched black butler uniform and sports a monocle on his left eye.
Clind is well-mannered, highly considerate of others, is extremely skilled as a servant, and tends to add idioms to the end of his sentences. Despite his good traits, he sometimes jokes around a little while behaving in a polite manner and is also a lolicon. However, he claims that he isn't drawn to them because they're young but rather because they have pure and genuine souls and people who have such souls are typically young. Because of this, he was able to determine that Emilia was mentally young for her age and that Ryuzu's soul was much more mature than her appearance suggested. Although he has known Frederica for ten years starting from the time he began working as a manservant, he tends to be prejudiced toward her appearance, resulting in bad relations between the two of them.
For over four centuries, Clind has presumably been acting as Roswaal's butler, even being entrusted with the knowledge of Roswaal's body-switching technique.
Following the end of the Demi-Human War, Clind accompanied Roswaal J Mathers (Julia Mathers) to a pub where she met with Wilhelm and discussed the topic about Stride with the Sword Demon. During their talk, however, the trio were assaulted by a group of Shinobi, who were swiftly dispatched by Roswaal, Wilhelm and Clind. Wilhelm noted that Clind's technique was neither sword skill or magic, but something completely else.
Following Roswaal's death at the hands of Stride Vollachia and his Shinobi, Clind was tasked with taking care of her son, Roswaal K Mathers (Karl Mathers), who also inherited the soul of the original Roswaal A Mathers (Altair Mathers). The duo's only appearance can be traced back to the end of Battle Ballad side story, as Wilhelm met them on Roswaal J Mathers' wedding. During their short exchange, Wilhelm swore he'll do everything in his power to help Karl if in need, in order to honour Julia who greatly helped him during and after the Civil War. Minutes after, Karl and Clind left the cemetery.
Some time in the following decades, Clind has been entrusted with protecting and training Frederica Baumann. During that period, he was also transferred to Miload Manor, where he acted as Annerose Miload's butler.
Skilled Swordsman: Clind is talented enough with the sword that he can fight in emergencies, though he's almost never seen wearing a sword or engaging in a sword fight.
Parkour: Clind is skilled enough at parkour to teach it to Subaru. Subaru mentions that he is able to finish the Athletic Zone Garfiel made without rumpling his clothes and without breaking a sweat, calling him a monster.
Survival skills: He is mentioned by Subaru as being skilled at survival, enough to be able to teach him the basics (finding water, how to start a fire, ect).
Whip: Like his parkour, Clind is skilled at using a whip and taught Subaru the basics on how to use one.
Unknown Authority: Clind possesses an Authority that allows him to cause damage to distant objects, though the process which he does this by is unknown. He can, for instance, use this ability to crush people's limbs. It should be noted, however, that Clind has been observed clenching his first before crushing the enemies, as well as stating the word "melancholy" right before using it–something distinct to Hector, the Warlock of Melancholy, who lived before the Great Calamity.
- According to the author, Clind is fond of both boys and girls, as his view on love is rather unique.
- It's been heavily hinted that Clind accompanied Roswaal J Mathers on her campaigns during the Demi-Human War, using some sort of cloaking ability, which made it so no one ever detected him.
- "so even when beast-changed, she retains her reasoning. Clind prepared her." Garfiel Birthday Q&A
- "To be enraptured by pure, immaculate souls is natural. And it happens that many possessors of such souls are young." One Day II Chapter 2. Section 1.
- "Subaru had Clind watch him practise his parkour, the then Clind defeated Garfiel's obstacle course without breaking a sweat and without ruffling his clothes. He's inhuman." Arc 5: Chapter 3. Section 1.
- "Edible grass and fruits are.... ahh, I was right to learn it from Clind-san. Gotta thank my mentor..." Arc 7: Chapter 1. Section 3.
- "Whips had a longer range and were more difficult to manipulate than movies had made them seem, but in the past year, under Clind's tutelage, Subaru's skill had vastly improved." Arc 5: Chapter 20. Section 1.
- Re:IF Kasaneru
- "In fact, the assassins which Clind had defeated were all dead, but he couldn't ascertain how they'd died from just looking. Their causes of death didn't seem to be from either a sword, a blow or magic from what he could see." Sword Demon Battle Ballad: Act 1. Section 4.
- Golden Siblings
- "Clind-san can go for boys, too." askFM Q&A
- "Quite so. Gratitude. But in fact, I was at Madam’s side as well during the Civil War. I turned myself invisible so that people wouldn’t see me. Concealment." Sword Demon Battle Ballad Act 1; Part 4