In the Daily Dose of Greek video for John 21:9, Dr. Plummer mentions almost as a side note that ἀνθρακιά ("charcoal fire," in the accusative form in the verse) occurs only twice in the Bible: in this verse and in John 18:18.
At first, I didn't give much thought to this, but the day after I watched the video, I realized that the contexts in which this word appears are related.
In John 18:18, Peter is standing by a charcoal fire while the soldiers take Jesus to Annas. In the surrounding verses (17, 25-27), Peter three times denies knowing Jesus.
In John 21, after the charcoal fire is mentioned, Jesus three times asks Peter if he loves Him (verses 15-17). The three instances (three denials and three questions) link these two passages, as John 21:17 makes clear ("Peter was grieved because he said to him the third time, 'Do you love me?'"), and while the charcoal fire isn't nearly as significant, it's a sensory detail that also connects these two accounts.
