Well unfortunately I don't have the knowledge or the resources.
However, I will tell you what both ideas are about.
There is no such thing as courage potions, this is actually a failed alchemical project (essence of Berserker) this is made with physical remains and fragments of the soul of a Berserker who was brought to misfortune by a friend (yes a reference to berserk) this is divided into ampoules which can only be used during the events of the game (the first one will make you confess your feelings).
This will make him act in events like the one about his love and the suspicious wolf.
The potion not only gives him the mental strength but also gives him physical strength and improves the technique of the sword (by the Berserker) also degrades his consciousness and merging it with the protagonist.
Now the gift of gray, is something simpler this would have 2 versions.
After the first encounter either with if the vial was used (which in that case would be released when fighting the wolf). During the encounter with the gray wolf almost at the end of the arc simply have the protagonist let himself be wounded (making his Hp reach 0) at the end of combat and in the moments after this will manifest slight symptoms of lycanthropy (normal if you are not under the effect of the vials of courage, or a more aggressive version which can not control).
Like I said these 2 ideas revolve around this game specifically because as I said they are ideas to create routes there ends my idea and that's where you decide whether to use them or not.