Dr. Delbert Doppler

Dr. Delbert Doppler is a major character in Treasure Planet. He is an alien with the appearance of being some kind of dog/human hybrid, and a notable and well-off astronomer. Doppler is also a longtime friend of Sarah Hawkins, and becomes the guardian of her son, Jim Hawkins, during the expedition to find Treasure Planet.

Personality
Dr. Delbert Doppler is seen as the classic astronomer who trips over his own feet and words yet seems to be one of the smarter characters, despite his choices in fashion. He is relatively pacifistic, not handling weapons if he can possibly avoid it. He is also very kind as he cares for both Jim and Sarah and was more than willing to let them stay at his house when their own inn was destroyed. As a scientist, he loves making new discoveries and exploring which was why he was so excited to explore the map. He can be a bit paranoid considering the suit he wore on his first day out in space. He also is socially awkward as shown through his interactions with Captain Amelia and the crew. He doesn't take kindly to insults, as shown when Captain Amelia insulted him. Deep down, he feels he is useless as he couldn't fight, didn't know how to properly attend to Captain Amelia's wounds, and couldn't find a way to help Jim and Captain Amelia when the crew betrayed them. However, he is very brave and loyal, managing to protect his friends and stand up to the bad guys when the situation called for it. He is also fairly intelligent, which has proven useful during the time the crew were stuck in the middle of the blackhole and his research and predictions of the outburst of the black hole allowed Captain Amelia a way to pilot out of the blackhole, which she commended him for.

Role in the film
Delbert Doppler is a long time friend of Sarah Hawkins, Jim’s mother, and after the BenBow Inn burnt to the ground he housed her and Jim without hesitation, saying they could stay as long as they needed to. When finding out about the map's potential, Doppler immediately agreed to go searching for the treasure with Jim, convincing Sarah it was a good idea. He pointed out to her wisely that he wasn't just doing it because he wanted to go; a few character-building months in space might help with Jim's increasingly rebellious nature.

Doppler funded the trip. After arriving at the space port on Montresser both Jim and Delbert came to accompany the ship to Treasure Planet, Delbert in what he assumed was an appropriate ‘Space Suit’ sold to him by a two headed sales woman.

When running into one of the many pirates, Jim was unable to understand what the alien was saying, until Doppler who was fluent in ‘Flatula’ was able to talk to the alien and even making him laugh. When he confused Mr Arrow for the captain he was quickly corrected, and watched in astonishment as Captain Amelia flew through the ship to land right in front of him.

Amelia’s appearance caught the doctor off guard but what seemed to irritate him more was the fact that Amelia found it enjoyable to poke fun at his space suit. When Doppler almost let the secret of the Map slip Amelia told him to meet her in her stateroom, where she scolded him for openly talking about treasure, and told him about her displeasure with his choice of crew, starting the apparent hate relationship between the two.

The taking off of the ship was an event for Doppler and while he tried to photo a flying whale (Orcus Galacticus), Amelia warned him about the whale's blowhole, though her warning came too late and Doppler was sprayed all over by the whale's breath. Nevertheless the doctor chose to take the picture anyway and Amelia did not seem to think badly about his clumsiness.

During the black hole disaster, Doppler, with his calculations of the waves, accurately predicted the outburst, and enabled Amelia to navigate through and make good their escape. Trying to compliment Amelia, Doppler is instead commended by the captain. Completely flustered and tripping over his words again, Doppler tried to offer his further service but in the process made a fool of himself. At this point it is hinted that he was having feelings for Amelia.
 * Doctor Doppler: "Captain, that was, that was the most..."
 * Captain Amelia: "Oh, tish-tosh. Actually, doctor, your astronomical advice was most helpful."
 * Doctor Doppler: "Well, thank you. Thank you very much. Well, I have a lot to offer anatomically... amamomically... astronomically."

As the ship reaches Treasure Planet, Silver and the pirates finally show their true colors, forcing Jim, Amelia and Doppler to defend themselves. It became apparent that Doppler never held a gun in his life as he almost shot Amelia. The doctor was expectedly clumsy during their escape, but when trying to abandon ship in a smaller boat, Doppler found his talent with a pistol when he was able to send several pirates to the planet below. In the ensuing sequence he and Amelia shot off the cables holding the longboat and escaped from the Legacy.

The boat crash landed on the planet and Amelia was badly wounded. As Doppler took gentle care of her it is revealed that the captain reciprocated his feelings, when Doppler explained to B.E.N. that they were not a couple, she looked at him meaningfully; and again when she flirted and encouraged him to "say something else" rather than concerns for her injury. The captain's injury worsened and she fell into a state of semi-consciousness. Distressed over his inability to help Amelia, Doppler had a small break down:

Doctor Doppler: ''Dang it, Jim. I'm an astronomer, not a doctor! I mean, I am a doctor, but I'm not that kind of doctor. I have a doctorate, it's not the same thing. You can't help people with a doctorate. You just sit there and you're useless!''

Afterwards Jim went back to the Legacy in search of the map while Doppler stayed with Amelia, but both of them were later captured and held hostage by Silver. Doppler seemed more concerned about keeping themselves alive when Silver threatened to kill the hostages if Jim refuse to activate the map. But when he saw Amelia firmly shook her head he shifted from nodding to shaking as well. Eventually Jim decided to put the lives of his friends ahead of the treasure and activated the map. When he and Amelia were left with a single guard while Silver and Jim went to find the treasure, Doppler lamented that he was completely useless, while Amelia tried to comfort him and replied that he was truly useful. However he then noticed his hands had come loose from their bindings behind his back. From there he was able to escape by tricking the alien holding them prisoner out of his pistol.

Doppler and Amelia managed to take back the control of the Legacy and piloted it back to pick up Jim. Doppler took the helm throughout the their escape as Amelia was too hurt to do so. The doctor however was unexpectedly good with a wheel in his hand and narrowly escaped numerous obstacles on their way.

With the help of Jim, the cast was able to make it back to the port, where Doppler and Amelia shared a hug with him rubbing his face on hers. Realizing what he just did Doppler withdrew, but the couple did not break from the hug and accepted their feelings for each other.

In the final scene of the movie, Doppler was present with Amelia at the opening ceremony of Sarah's new inn , and is seen standing with Amelia at the party, holding 3 feline babies that look similar to Amelia, while Amelia is holding a canid baby boy. Treasure Planet's art book A Voyage of Discovery reveals that Doppler and Amelia are "happily married" at the end of the movie.

The ending of the movie was proving a point to the audience that after so much hardship that all the characters were better off, including Doppler as he now had a family and a life partner, Amelia.

Trivia

 * A few lines cut from the end of the movie reveal that it was actually Dr. Doppler who gave birth to their children. It was cut due to Disney thinking a male pregnancy would be too risque to be put in a children's movie.
 * It is revealed in Disney's 365 Bedtime Stories (Page 292) that Doppler and Amelia's four children are named Matey, Jib, Tillie and Sunny.
 * During his small breakdown, Doppler shouts "Dang it, Jim. I'm an astronomer, not a doctor!": this is a clear reference to the Star Trek character Doc "Bones" McCoy, who usually shouted "Dammit, Jim! I'm a doctor, not a..." followed by the required profession.