Professor Booster

Professor Booster (ブースター博士 Būsutā Hakase) is a professor from the research team that went to the Island. When the Doctor gained control of the Demon Crown, he put Kazuma and Booster in jail. Kazuma managed to escape to a teleporter (most likely the one from Jail No. 2) warping him to Bushlands. He acts as Sue's grandfather figure.
==Story==
After the player blows up the rusted door trapping Kazuma in a shelter, Professor Booster appears from the teleporter, having escaped the Doctor. After a conversation with Kazuma, the two go outside and ride a motorbike to get out of the Bushlands. They quickly lose control, however, and fly off-screen. The bike they rode is then found crashed in front of Santa's House, although the two seemingly made it out of the crash unscathed as they made it to Arthur's House. After Sue, King, and the player all convene with them at Arthur's House, they discuss several things, such as the Doctor finding the Red Flowers, and Booster also reveals that the player is a robot (something that the other characters hadn't realized). He then sends you off to the Sand Zone to destroy the Red Flowers before the Doctor can get to them. 
Later, while you're stuck navigating through the Labyrinth, Misery zaps him into the pit right after Monster X. If the player drops down as well, Booster, who is in very bad shape, will be surprised to see you, and reveals that you've been teleported near the heart of the island, which if destroyed will cause the island to cease functioning. Deciding that his luck has run out, he prays for your victory and, with his dying breath, gifts you his partially completed invention, the Booster v0.8, before dying shortly after, having presumably given up. This course of events will lock the player out of the "best" ending, forcing you to get either the "normal" or "bad" endings. 
If the player instead jumps over the pit (it can be tricky, so it's recommended to save before trying. A fully upgraded Machine Gun also trivializes the jump if you traded for it previously.) then Booster will not give up and keep living, likely due to not knowing you've survived to be able to set things right. After the player escapes the labyrinth, Booster will be found teleporting into Arthur's House, having fixed the broken teleporter at the bottom of the pit. He makes a final request for you to find Sue and flee the island her, stating that she never wanted to come to the island in the first place. He also gives you the Booster v2.0, an upgraded version of his Booster v.0.8. Taking this course of events is one of the requirements for getting the "best" ending of the game, as the Tow Rope will not appear in the Core Room if Booster died.
For the remainder of the game, Booster will reside at Arthur's House, repeating his plea to save Sue if spoken to. If talked to while wearing the Mimiga Mask, he claims humans ruined the island, and therefore are evil. If he survived the course of the game, then during the credits Booster will be shown arriving at Jenka's house in the Sand Zone. If he died (not possible in "best" ending), the door to her house will not open and no one else will arrive.
== Gallery ==
File:Booster20th.png|Professor Booster in Nicalis' Cave Story 20th Anniversary Message
==Trivia==
*Professor Booster is one of the only characters in the game who can have a different fate in a single ending, due to being able to be either alive or dead in the "normal" ending. Most other characters have a single fate depending on the ending (Kazuma, for instance, lives in every ending while King dies in all of them), or otherwise always have their fates left vague, such as with Jack.
Category:Allies