Maybe Athos is jealous of Aramis. For example, if Aramis gets more attention from a certain person they both care about, like a mutual friend or a love interest. This jealousy could lead him to say or do things that unintentionally or even intentionally hurt Aramis's feelings.
There might be some past trauma or personal issues that Athos has. If he had a bad experience in the past that is somehow related to Aramis's actions or personality traits, it could trigger him to lash out and hurt Aramis's feelings. For example, if Athos was betrayed by someone with similar characteristics as Aramis in the past, he may project those negative feelings onto Aramis.
It could be due to a misunderstanding. Suppose Aramis did something that Athos misinterpreted. For instance, Aramis was helping someone in secret, and Athos thought he was being sneaky for a bad reason. So, in his anger or confusion, Athos might have hurt Aramis's feelings without really knowing the whole truth.
Aramis could choose to confront Athos directly. He might say something like 'Athos, what you did really hurt me. I don't understand why you would say such things.' This way, he gives Athos a chance to explain himself and they can start to resolve the issue.
One possible scenario could be that Athos made a critical comment about Aramis' skills in combat. For example, he might have said something like 'Your swordplay lacks the necessary precision lately, Aramis.' This could really hurt Aramis as he takes pride in his combat abilities. It could lead to a rift between them, with Aramis feeling betrayed by his friend's lack of support and confidence in him.
First, Athos needs to realize the full extent of the hurt he has caused. He should approach Aramis sincerely and apologize. For example, he could say 'Aramis, I was wrong. My words were thoughtless and I deeply regret hurting you.' This simple act of acknowledgment can be a first step towards healing the relationship.
One idea could be a story where Athos, Porthos, and Aramis go on a secret mission together. They face many challenges and have to use their unique skills to overcome them. For example, Athos' calm leadership, Porthos' strength, and Aramis' charm and intelligence all play a part in the success of the mission.
You can find athos aramis fanfic on some popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfics related to various fandoms, including the Musketeers, where you can easily search for athos aramis fanfic.
A great plot twist could be that one of them is secretly working for the enemy all along. For instance, it seems like Athos is on their side, but then it's revealed that he has been manipulated into helping the opposing force. This would shatter the trust within the group.
One popular athos aramis fanfic is 'The Bond of Brothers'. It beautifully explores their relationship, with well - written dialogues that bring out their loyalty and camaraderie. Another is 'A Musketeer's Journey' which delves into their adventures together in a very engaging way.
One possible plotline could be that Aramis is betrayed by a close friend. Maybe they spread false rumors about him, which makes him feel hurt and isolated. He then has to struggle with these feelings while trying to find out who is behind it all.
Show his actions. Maybe Aramis withdraws from social situations. He stops going to his favorite places or stops talking to the people he used to be close to. This shows that his feelings are so hurt that he wants to be alone.
It could be due to an unrequited love. If Aramis has feelings for someone in the fanfic who doesn't return those feelings, it can be a source of restlessness. He might be lying in bed, thinking about this person and how to win their heart, thus unable to sleep.