Responses

Well according to the recent chapters.. it seem he has regrets about his little sister death.. he's blaming himself for not trusting or protecting his sister.. so I think the reason he wants to protect mc is due to his own psychological problem maybe he thinks that if he protect mc(who look like his sister) the regret and self blaming would decrease a bit..
Just sharing my opinion. Please don't get triggered(≧∀≦) With my reader's instinct I feel that Sir Belgarde may be the main male lead for our protagonist. But from my viewpoint I don't really like his affection nature. Falling for someone because he or she resembles your loved one is not really my type.