Why is this not acceptable? Sie sucht für ihren Bruder.
Same. Why is "für" implied. That answer literally translates as "she search her brother". Does her brother have weapons on needles in his tasche that might stick me?
I thought that too. However, when I looked up suchen, it appears to mean "to search/look for" so I guess the "for" is part of the verb.
While it is optional, you have to use "nach" with "suchen." Be sure to use the dative as well.
"Sie sucht nach ihrem Bruder." is acceptable
Wouldn't 'suchen nach' sound better?
Duo also accepts: Sie sucht nach ihrem Bruder.