Possible Clues:

• Like the lines in a Mondrian painting
• Move or be arranged in a lattice pattern
• What streets do on an urban map
• Type of grid that could make Christopher reportedly angry
• Pass back and forth over
• Caught start of rugby scissors manoeuvres intersecting
• Heard Christopher briefly angry — a pattern
• On the radio, Christopher angry with lines cutting across one another
• Shoelaces do this
• Intersect