Char Rom behaves weird, as from the processors point of view normally its invisible, and if you turn it on the CPU “sees” it always at D000-E000. 
The VIC sees the char ROM _always_ at the memory areas $1000-$2000 and $9000-$a000 making these ram areas unusable for storing gfx, as no matter what the VIC will read from the char ROM at these addresses.