return title
[line1] = plt.plot(list(range(10)))
[line2] = plt.plot(list(range(10, 0, -1)), 'o', color='red')
plt.legend(['Title 1', line1, 'Title 2', line2], ['', 'Line 1', '',
    'Line 2'], handler_map={str: LegendTitle({'fontsize': 18})})
plt.show()
Subtitles within Matplotlib legend