Possible Clues:

• They meet in an oxymoron
• Near and far, e.g
• Completely different pair
• River going this way and that to places hot and cold?
• Night and day, say
• Place maintained by friends who couldn't be more different
• Come and go, say, in workplaces around river
• With a little work to and fro, the web pages show up and down for example
• See 2-Down
• They're said to attract work on river locations