First, AES is not something that you want to use itself. AES is a pseudorandom permutation family, which is roughly academic cryptography jargon for ‘here be dragons—do not enter unless you are a wizard who can harness them’.
You want to use an authenticated cipher like AES-GCM or NaCl crypto_secretbox_xsalsa20poly1305, in which the dragons—along with other useful things—have already been harnessed into a useful security contract: if you pick a key uniformly at random and assign to each message a unique message number, for up to a gigabyte of data per message and about a terabyte of data total under a single key, then AES-GCM prevents an adversary who can intercept messages in transit from (a) learning what's in them in any more detail than their length, and (b) forging them.
(NaCl crypto_secretbox_xsalsa20poly1305 has a slightly better security contract—it's safer for much larger volumes of data, you can safely pick the message numbers uniformly at random, and it's designed to invite resistance to side channel attacks in software implementations, unlike AES-GCM.)
This security contract holds even if the adversary can choose the patterns of data in the message. The modern standard for secrecy of a cipher (IND-CPA, or indistinguishability under chosen-plaintext attack, which authenticated encryption implies) requires that the adversary be unable to find any pair of messages whose ciphertexts they can tell apart with more than negligible probability, even if given arbitrarily many other plaintext/ciphertext pairs of their choice.