It seems that
VIMRUNTIME are not used as akira said.
VIMINIT is used as an Ex command, so
VIMINIT=/home/user/.vimrc would try a search and give an errror like:
search hit BOTTOM, continuing at TOP
Error detected while processing VIMINIT:
E486: Pattern not found: home
VIMRUNTIME normally point to the location where vim's basic support files is installed, like
/usr/share/vim/vim73, so if it's redirected to /home/user/.vim, vim would lost many basic functions unless your vim is just installed to /home/usr/.vim.
:help -u and
-u vimrc option can specify the
.vimrc file but will skip most other initialization files, like system vimrc, eg.
/etc/vimrc. If the specified vimrc file does almost all jobs, then the shortcomming, if called this, is trivial.
:help runtimepath, pathes of
runtimepath will be searched for support files, so we can prepend
/home/user/.vim and append
runtimepath before soucing vimrc file using
--cmd options at startup.
To sum up, we can set up this alias to use ~/.vimrc and ~/vim:
alias vim='vim --cmd "set runtimepath^=/home/user/.vim" \
--cmd "set runtimepath+=/home/user/.vim/after" \
ps. Alternatively, two simple symbolic links may also work for you.
ln -s /home/user/.vimrc /root/
ln -s /home/user/.vim /root/