Help me choose a plant combination

Hi folks.

I need some help with deciding on plant combinations. I am building a long planter for privacy, approx 4m long, with a trellis to allow a climber to grow. I got some hellebore Niger plants very cheap last week so that's my start. I have to introduce a climber to grow up the trellis to give the privacy, and would like to add 2 or so plant species to compliment the hellebores and climber.

So - I would like to get your thoughts on what I could add to compliment the hellebores and a suggestion for climbers. To give you an idea of the site, it will be situated on a patio in a north facing garden, partial shade and zero sun during winter. Thanks for your time