Part I:
[Reason: Nel Tu is Nelliel's nickname in the series.]
Part II:
- aaroniero -> aaroniero arruruerie
- grimmjow -> grimmjow jaegerjaquez
- lilynette -> lilynette gingerbuck
- nelliel -> nelliel tu odelschwanck
- nnoitra -> nnoitra gilga
- ulquiorra -> ulquiorra cifer
[Reason:
I, personally, never remember exactly how to type most of these orthographically complex full names. I assume other people on the Internet don't care to remember them as well, because the full names rarely appear in online running text.
In addition, since these names have so odd spellings they are very unlikely to be ambiguous; they probably won't ever be used for characters of other series in the foreseeable future.]
EDIT:
Simplified the "reason" of the part II a lot.
Updated by jxh2154