OpenEuphoria

I should strongly recommend going the columnize() route, defining 5 and 'A' next to each other to start with, as per the pp(ic) outputs. Inserting/deleting the 3rd element of 54321 and ABCDE looks simple enough, but once they're 50+ elements long it gets to be a RPITA keeping two or more such sequences perfectly in step. Note that when I say "columnize() route", you should understand there is a reversibility about that:

sequence ic = columnize({{5,4,3,2,1},{'A','B','C','D','E'}}) 
ppOpt({pp_IntCh,-1}) 
pp(ic)              -- {{5,'A'}, {4,'B'}, {3,'C'}, {2,'D'}, {1,'E'}} 
pp(columnize(ic))   -- {{5,4,3,2,1}, {'A','B','C','D','E'}}