The Entity of The Forest
Finding Quite Wood, Mysterious Deku
Link discovers the deku from before was trying to kill him and Leafosa, and later on, this deku was just a mutated mad deku being control by someone. After defeating it, Link continued to venture the dungeon and finds the person in charge. A "figure from Link's memory" tried to confronts Link, however, Link jabbed the the figure in the gut, revealing that the the figure was really Blind, the entity that Link heard rumors about and the information in the abandon guard house. Link defeats Blind, obtaining a strange pendant in the process, immediately Link and company went back to Korri to discuss the matter.
The Old Cavern in the Forest
Link and Leafosa followed the deku and offered to help him with his unclear objective. After venturing inside, at some point, Leafosa got anxious and decided to depart from Link, thinking he can handle the matter himself. Link is left to venture the cavern alone. Link entered a room and found out Leafosa entered an old prison cell and is unable to escape, forcing Link to find the key/trigger to rescue him. Once he he set free, Leafosa remains by the entrance to the cell room, Link ventures to the next room where he spotted the unknown deku, who trapped Link inside the room and attempted to ambush him, revealing himself to be nothing but a shell deku, someone else in the background had been controlling it. The deku monster was defeated by Link, and the gel in the surrounding area. Link found a switch, which opens the door, but acquires to be triggered from a distance. Link gets the Hero's Bow and activate the switch to exit. Link and Leafosa meet again, Leafosa gives Link a special key to access a room in the basement. The two stumbled upon a figure, who needed their help to escape, Link attacks the figure and this figure raveled itself to be Blind Jr. (Blind the Theif in phantom form).
Link and Leaofsa defeats Blind Jr. and escaped the Cavern, after this event had happened, Leafosa rushed ahead to report this event to Korri Woodfall. Thanking Link for his efforts, he gives Link a letter of permission so he may leave the forest, granting him the ability to pass the deku guards. Before Link took off, he showed the unknown pendant to Korri and was given an explianation.
Special Event: Missing Deku, Ralts
The deku went missing sometime before Link unexpectedly appeared in Orlo Gale.
There was in fact a deku who went missing and only a few villager know about this, he was last seen in Quite Wood. Blind took up this persona easily and lead Link and Leafosa deeper into the Forest. Leafosa knew that the unknown deku could have something to do with the missing deku, this explains why he didn't want to fallback when Link was present.
If the missing deku is saved, some villagers will thank you and offer some rewards for this, otherwise if the missing deku cannot be found before fighting the boss, he will be dead and missing and nowhere to be found, the player will notice this if the boss' speech is different after the fight.