Why did Robin become Nightwing?

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Tags

1. #death
2. #temporarily
3. #batman
4. #wayne
5. #subsequently
6. #apparent
7. #mantle
8. #dismissed
9. #featured
10. #teenager
11. #became
12. #after
13. #series
14. #robin
15. #retiring
16. #grayson
17. #nightwing