Following Professor Pickle's kidnapping by Dr. Eggman, many of David's classes were canceled, which therefore forced him on an indefinite break from his studies for the time being, though he did not know the reason why.
During the events of Sonic Unleashed, David met Sonic the Hedgehog and Chip when the duo came to Spagonia for the first time to look for Professor Pickle. Upon meeting the duo, David gave them a loud, but friendly greeting and asked them where they came from. Having learned that the Earth had been shattered, but still kind of out of the loop of news, David then asked Sonic and Chip if they knew what was wrong with the planet and requested that they should let him know about what they had learned about this crisis. When Sonic and Chip shortly after returned, David was initially surprised to hear that Professor Pickle had been kidnapped, but then danced in joy as it meant he did not have to take a test that Professor Pickle had planned. He quickly recomposed himself, however, and admitted that he had to be serious in such a situation.
As Sonic and Chip began traveling across the world and restoring it with the Gaia Temples, David somehow heard about their travels and their objective. When he later came across Sonic and Chip again, David told them about what he had heard about them and called them "global adventures". Sonic and Chip then revealed to David that they were the ones restoring the planet, but David thought they were only joking.
At some point afterwards, David became possessed by some of Dark Gaia's Minions. Their influence would then cause him to dance and party rowdy together with other possessed humans in the middle of the streets in Spagonia during nighttime, though he would revert to normal during daytime. Luckily, David and the rest of the possessed people had Dark Gaia's Minions exorcised from them by Sonic the Werehog and Chip during their first exorcism, thus freeing him from their influence.
Sometime after this experience, David had a conversation with Lilli about Raimondo's and Federica's supposed relationship, where he revealed to Lilli that he had heard that they were going to Apotos together, much to Lilli's shock.
At some later point afterwards, David was approached by dorm master Otto who asked him to cheer up Dora, who was very shy and lonely. David was not thrilled by this, however, as he had no idea what to do. Nevertheless, David met up with Dora and asked her if he remembered him, since they attended the same science class. He then asked her, rather awkwardly and clumsily, if she wanted to hang with him, just the two of them. Dora asked him if he really meant her and if he had not mistaken her for some other girl, but David confirmed it was her and said that he thought she would like to hang out if she wanted, with Dora saying that she would love to. As the two of them hang out together, they came to have a great time with each other, and David began to view their time together as a date. David himself told Dora that he thought she was funny during their date, and while he found her very shy, David thought she was a sweet girl. Not long after, David began to develop feelings for Dora.
Wanting to stay in touch with Dora, David tried to meet up with her again. Dora on the other hand, tried to stay away from David as she did not think that David loved her, since it was Otto's idea with the date and not David's, and therefore tried to keep herself from getting too close to him, as she was starting to have feelings for him as well. David tried to look for Dora throughout Spagonia, but she was nowhere to be found and when he tried to call her, his messages was ignored. Distraught and worried, David found Sonic and asked him sadly if he could ask him about Dora to figure out what wrong. After hearing what Sonic had to say, David resolved to find Dora and set things right between them.
David eventually managed to meet up with Dora. He told her how he had been looking all over for her and asked her why she was avoiding him. He then told her, though he struggled with it, that he had been worrying about her and confessed that even though it was Otto's idea for them to meet, he had not been able to get her out of his head since. Now having confirmed his feelings for her, David asked her carefully if she wanted to go out on another date with him, to which Dora happily answered that she was so happy to hear what he had just told her.
David never made any real appearance during the PS2/Wii version of Sonic Unleashed, and only appeared during the cutscenes. During the events of Sonic Unleashed, David became possessed by some of Dark Gaia's Minions. Their influence would then cause him to dance and party rowdy together with other possessed humans in the middle of the streets in Spagonia during nighttime, but would then revert to normal during daytime. Luckily, David and the rest of the possessed people had Dark Gaia's Minions exorcised from them by Sonic the Werehog and Chip during their first exorcism, thus freeing him from their influence.