Goo Dong-mae.

Goo Dong-mae, one of the main characters of the Korean series Mr. Sunshine, is a man of intimidating appearance and complex personality. Physically, he has a robust and muscular figure, with long, dark hair, usually tied back. He usually dresses in black, with a long coat and Japanese-style details, reflecting his affiliation with the samurai and his training in Japan. His gaze is hard, and he always carries a sword with him, a symbol of his prowess and constant threat.

As for his personality, Goo Dong-mae is cold, distant, and seemingly ruthless. He is a tragic character who has suffered a lot in his life, which has made him a lonely and vengeful being. Although he seems to have a cruel and violent attitude, deep down he is someone with a code of honor. He is also shown to be deeply in love with Ae-shin, which reveals his most vulnerable side and gives him nuances of humanity. His loyalty towards her leads him to make decisions that reflect his inner emotions, despite his tough facade.

He is a character full of contradictions: fierce, but with a deep emotional wound, which makes him fascinating and tragic.

In a relationship, Goo Dong-mae would be someone passionate but complicated. Given his emotional background and the nature of his personality, he wouldn't be easy to understand or approach at first. His reserved nature and tendency to remain emotionally distant would make it difficult for him to open up or express his feelings directly.

However, once he becomes emotionally attached to someone, his loyalty would be unwavering. As seen with his love for Ae-shin in Mr. Sunshine, Dong-mae can be incredibly devoted and protective. His love is not necessarily expressive or sweet, but rather an intense way of caring and looking out for the well-being of the person he loves, even sacrificing his own interests.

Given his character, it would not be easy for him to show affection in a conventional way, and his partner would need patience to understand him. His expressions of love would probably come in the form of actions – protection, sacrifice and support in difficult times – rather than traditional romantic gestures. There could also be moments of tension due to his possessive and protective nature, as his fear of losing the person he loves could lead him to be overprotective.

In short, in a relationship, Goo Dong-mae would be an intense and loyal partner, but with emotional challenges that would require patience, understanding and acceptance of his complex nature.