If we wanted to match a single character, our pattern would be /a./. The control character is a '.' after the letter in question.

No! /a./ means match two characters, an 'a' followed by any other character. To match a single lower-case 'a', the pattern is simply /a/ - try it and see:

$_ = 'He lives in Liberia';
print    'with dot: ', $_ if /a./;
# No output
print 'without dot: ', $_ if /a/;
# Outputs 'without dot: He lives in Liberia'
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Also, in your last paragraph, you've inverted your square brackets and slashes...

Update:

To clarify, the dot (period) is not a 'control character', as you seem to imagine, but a 'wildcard character'. To quote from perlretut (which I highly recommend you read, and include in your list of other sources):

The period '.' matches any character but "\n"

Update2: s/perlreftut/perlretut, sorry!