Well, without having read the 'alvin the treacherous fanfic' directly, it could center around the character Alvin's untrustworthy nature. Maybe it shows how Alvin's treachery affects other characters in the story. It could be set in a world where his actions create chaos, or it might be a more psychological exploration of what makes him treacherous and how others react to it.
I'm not certain as I haven't read it, but likely Alvin is one of the main characters since he is in the title. There could also be characters who are affected by Alvin's treachery, like friends or foes.
In a fanfic where Alvin is in prison in the 'Alvin and the Chipmunks' universe, it could be a really interesting take on his character. He might face challenges from other inmates who don't like his upbeat and sometimes mischievous nature. However, Alvin could also bring some positive change to the prison, like starting a music group among the inmates to pass the time and boost morale.
One possible reason for Alvin's depression in a fanfic could be the pressure of constantly being in the spotlight. As the lead chipmunk, he always has to be on top of his game, whether it's performing or coming up with new ideas. This unending stress might lead him to feel down. For example, in a big concert coming up, he might feel like he's not good enough and start to doubt himself, which could be a start of his depressive state.
In Alvin x Simon fanfiction, they might go on an adventure together. For example, they could get lost in the forest while trying to find a special type of nut for a recipe. During their time lost, they rely on each other's skills. Alvin uses his quick thinking and physical abilities to get them out of some tricky situations, like crossing a small stream. Simon, on the other hand, uses his knowledge of the forest's flora and fauna to find food and shelter. Through this adventure, their bond grows stronger.
In an 'Alvin and the Chipmunks' Alvin prison fanfic, Alvin could face a lot of difficulties at first. He is used to a life full of freedom and fun with his brothers. In prison, he might be lonely and scared. But as time passes, he could learn to adapt. He could teach the other inmates about music and harmony. His positive attitude could gradually change the prison culture. He might even find a way to communicate with his brothers outside, through secret messages or smuggled notes, and they could be working on a plan to get him out.
A great Alvin smart fanfic might be where Alvin figures out a way to save the Chipmunks' tree house from being demolished. He uses his intelligence to find a legal loophole or comes up with a brilliant plan to raise enough money to buy the land it's on. For example, he might organize a huge concert with the Chipmunks and use the proceeds for this purpose.
One possible plot for such a fanfic could be that Alvin gets separated from the group during a concert tour. He might find himself in a small town and has to rely on his wits to get by. He could meet new friends who initially don't believe he's a famous chipmunk but eventually help him reunite with his brothers.
Well, in this fanfiction where Alvin gets sick, it could start with Alvin waking up one day feeling really unwell. He has a high fever and can't even sing his favorite tunes. Simon, being the smart one, tries to diagnose what's wrong with him using his vast knowledge. Theodore, on the other hand, is just worried sick and keeps bringing Alvin his favorite snacks, thinking that will make him better. As the story progresses, they might face some challenges like not being able to find the right medicine in time or having to deal with Alvin's crankiness due to his illness.