Is Gaster related to Sans and Papyrus?

Related questions

1. Can I play Deltarune before Undertale?
2. What is Underfell?
3. Do you have to kill Toriel?
4. Is Deltarune actually Undertale 2?
5. Who is sans the skeleton?
6. What is Underfresh?
7. Does Xbox have Deltarune?
8. How tall is sans Undertale?
9. What is Echotale?
10. How do I beat papyrus?

Tags

1. #named
2. #mysteryman
3. #redacted
4. #speaks
5. #different
6. #unconfirmed
7. #lowercase
8. #respectively
9. #actually
10. #theory
11. #gaster
12. #papyrus
13. #after
14. #while
15. #fonts
16. #which