Complex sentence: Jon suspects this was due to Ser Alliser Thorne, as revenge for Jon defying him; however, his friend Samwell Tarly (John Bradley) assures Jon that being the Lord Commander's steward might help groom him to be the next Lord Commander.
Split into simpler sentences: Jon suspects this was due to Ser Alliser Thorne, as revenge for Jon defying him. However, his friend Samwell Tarly (John Bradley) assures Jon that being the Lord Commander's steward might help groom him to be the next Lord Commander.