1882. Italy joins Germany and Austria-Hungary in forming The Triple Alliance. Historically, Italy was never a strong partner in this grouping, and when bullets began to fly in 1914, Italy asserts her neutrality, eventually joining the war against her former allies.
Suppose a few events are tweaked. A less belligerant Austria into peninsular affairs, a more reasonable Pius IX who supports Italian unification, Italian non-involvement in the Austro-Prussian War of 1866, etc., and perhaps an Italy emerges that has no harsh regard towards Austria. A possible result? The Italians remain in the Triple Alliance as a forceful member looking for colonial gain.
How does World War One change when its Triple Entente vs. Triple Alliance?