Dreamy

He's literally made of goodness. Dream is incapable of hatred, even his own brother. This doesn't mean he's weak-willed: he resolutely protects the universes and those who live in them.
He senses the emotions of others. Due to his nature, he is attuned to the feelings of those around him, and through his extensive travels across the multiverse, he has learned to identify where negativity accumulates and seek to correct it.
His strength depends on his environment. In happy, bright universes, he becomes stronger, faster, and can even heal better. But in dark worlds like DustTale or HorrorTale, he weakens and risks death.
A special relationship with Ink. Dream collaborates with Ink!Sans: Ink creates and maintains alternate universes, while Dream brings positivity to them and helps maintain balance. However, they have different worldviews: Ink doesn't always interfere with the fate of worlds, while Dream can't stand to see anyone suffer.
Interesting details
494 years in stone. After the disaster with the Tree of Feelings, Dream was sealed in stone. He didn't sleep, but all this time he felt the growing negativity throughout the multiverse and suffered from the fact that he couldn't help anyone. Hence his childish innocence: he simply didn't have a normal upbringing.
When he's happy, his pupils turn into stars. It's a small but very recognizable detail that fans love to depict in their artwork.
Dream and Nightmare share this birthday on December 21st, and it's often celebrated in the fandom.
The golden cloak was a gift from his brother. It sounds unexpected, but before the tragedy, Nightmare gave Dream this cloak. Now it's both a symbol of their bond and a reminder of what they lost.